Compact fuel cell package

ABSTRACT

The invention relates to a compact and portable fuel cell package. The package includes a fuel cell that generates electrical energy. Some packages also include a fuel processor that produces hydrogen from a fuel source. Fuel cell packages described herein provide power densities (power per unit volume or mass) at levels not yet seen. One package employs an interconnect disposed at least partially between a fuel cell and a fuel processor. The interconnect forms a structural and plumbing intermediary between the two. Given the portable size of fuel cell packages described herein, the invention is well suited to power portable electronics devices. One portable fuel cell package includes a tether, which allows electrical and detachable coupling to an electronics device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 11/120,643, filed on May 2, 2005, which claims priority under 35U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/638,421filed on Dec. 21, 2004 entitled “Micro Fuel Cell Architecture,” both ofwhich are incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to fuel cell technology. In particular,the invention relates to fuel cell systems included in a compact andportable package suitable for powering portable electronic devices.

A fuel cell electrochemically combines hydrogen and oxygen to generateelectrical energy. Fuel cell development so far has concentrated onlarge-scale applications such as industrial size generators forelectrical power back up. Consumer electronics devices and otherportable electrical power applications currently rely on lithium ion andsimilar battery technologies. Fuel cell systems that generate electricalenergy for portable applications such as electronics would be desirable,but are not yet commercially available. In addition, technology advancesthat reduce fuel cell system size would be beneficial.

SUMMARY OF THE INVENTION

The present invention relates to a compact and portable fuel cellpackage. The package includes a fuel cell that generates electricalenergy. Some packages also include a fuel processor that produceshydrogen from a fuel source. Fuel cell packages described herein providepower densities (power per unit volume or mass) at levels not yet seenin the fuel cell industry. For example, one portable fuel cellpackage—including both a fuel cell and fuel processor—occupies less thanone liter and provides 30 Watts of electrical output. Lesser volumes anddifferent electrical outputs are possible with packages describedherein.

One package employs an interconnect disposed at least partially betweena fuel cell and a fuel processor. The interconnect forms a structuraland plumbing intermediary between the two. One or more conduits traversethe interconnect and permit gaseous and/or fluid communication betweenthe fuel cell and the fuel processor. The interconnect reduces plumbingcomplexity and space, which leads to a smaller package.

Some fuel cell packages are designed to power an electronics device.Given the portability of fuel cell packages described herein, theinvention is well suited to power portable electronics devices such aslaptop computers.

One fuel cell package includes a tether. The tether allows electricaland detachable coupling with an electronics device so as to supplyenergy generated by the fuel cell, or to supply energy stored in arechargeable battery included in the package and charged by the fuelcell.

The fuel cell package may also include insulation to decrease heat lossfrom the fuel cell and fuel processor, which both typically operate atelevated temperatures. The insulation increases thermal efficiency ofthe package.

In one aspect, the present invention relates to a fuel cell package forproviding electrical energy. The fuel cell package includes a fuel cellconfigured to receive hydrogen and oxygen and to generate electricalenergy. The fuel cell package provides a power density of greater thanabout 30 Watts/liter according to a volume of the fuel cell package.

In another aspect, the present invention relates to a fuel cell packagethat produces electrical energy from a fuel source, such as methanol.The fuel cell package comprises a fuel processor that includes areformer and a heater. The reformer receives the fuel source, outputshydrogen, and includes a catalyst that facilitates the production ofhydrogen from the fuel source. The heater generates heat for transfer tothe reformer. The package also includes a fuel cell that generateselectrical energy using hydrogen output by the fuel processor.

In yet another aspect, the present invention relates to a compact fuelcell package. The fuel cell package includes a fuel processor, a fuelcell and an interconnect disposed at least partially between the fuelcell and the fuel processor. The interconnect includes a set of conduitsthat each communicate a liquid or gas between the fuel processor and thefuel cell.

In still another aspect, the present invention relates to a tetheredfuel cell package. The tethered package includes a fuel cell and ahousing that at least partially contains the fuel cell. The package alsoincludes a tether capable of electrical coupling to an electronicsdevice and transmitting electricity generated by the fuel cell to theelectronics device.

In another aspect, the present invention relates to an insulated fuelcell package. The package includes a fuel cell, a housing, andinsulation disposed at least partially between the fuel cell and thehousing.

In yet another aspect, the present invention relates to an interconnectfor use in a fuel cell package that includes a fuel processor and a fuelcell. The interconnect is disposed at least partially between the fuelcell and the fuel processor and includes a set of conduits that eachcommunicate a liquid or gas between the fuel processor and the fuelcell. The set of conduits includes a hydrogen conduit that receiveshydrogen from a hydrogen channel in the fuel processor and outputs thehydrogen to a hydrogen channel in the fuel cell.

These and other features and advantages of the present invention will bedescribed in the following description of the invention and associatedfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a fuel cell package for producing electrical energyin accordance with one embodiment of the present invention.

FIG. 1B illustrates a fuel cell package including a fuel processor inaccordance with another embodiment of the present invention.

FIG. 1C illustrates schematic operation for the fuel cell package ofFIG. 1B in accordance with a specific embodiment of the presentinvention.

FIG. 2A illustrates a simplified cross sectional view of a fuel cellstack for use in the fuel cell of FIG. 1A in accordance with oneembodiment of the present invention.

FIG. 2B illustrates an outer top perspective view of a fuel cell stackand fuel cell in accordance with another embodiment of the presentinvention.

FIG. 2C illustrates an ion conductive membrane fuel cell (PEMFC)architecture for the fuel cell of FIG. 1A in accordance with oneembodiment of the present invention.

FIG. 2D illustrates a top perspective view of bi-polar plates inaccordance with one embodiment of the present invention.

FIG. 3A illustrates an outer top perspective view of a fuel processorused in the fuel cell system of FIG. 1A.

FIG. 3B illustrates a cross-sectional front view of a main component inthe fuel processor used in the fuel cell system of FIG. 1A taken througha mid-plane of fuel processor.

FIG. 4A illustrates an outer perspective view of a fuel cell package inaccordance with one embodiment of the present invention.

FIG. 4B shows a perspective view of internal components of a coplanarfuel cell package in accordance with a specific embodiment of thepresent invention.

FIG. 4C illustrates a perspective view of internal components for a fuelcell package in accordance with another specific embodiment of thepresent invention.

FIG. 5A illustrates a perspective view of an interconnect for use in afuel cell package in accordance with one embodiment of the presentinvention.

FIG. 5B shows the interconnect of FIG. 5A attached to a top plate of afuel cell.

FIG. 5C illustrates the underside of a top plate that couples to theinterconnect of FIG. 5A.

FIG. 5D shows a side view of the interconnect of FIG. 5A and exemplarydimensions of its internal plumbing.

FIG. 5E illustrates a top view of the interconnect of FIG. 5A and anexemplary arrangement of ports on one surface that provides a uniquecoupling interface with the interconnect.

FIG. 5F illustrates an expanded view of the interface between theinterconnect of FIG. 5A and the top plate of a fuel cell.

FIG. 6 shows a perspective view of insulation disposed about internalcomponents of a fuel cell package in accordance with a specificembodiment of the present invention.

FIG. 7A shows a simplified illustration of a tethered fuel cell packagein accordance with one embodiment of the present invention.

FIG. 7B illustrates an internal perspective view of the tethered fuelcell package of FIG. 7A in accordance with a specific embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described in detail with reference to a fewpreferred embodiments as illustrated in the accompanying drawings. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process steps and/or structureshave not been described in detail in order to not unnecessarily obscurethe present invention.

Fuel Cell Package

FIG. 1A illustrates a fuel cell package 1 for producing electricalenergy in accordance with one embodiment of the present invention. Fuelcell package 1 comprises a fuel cell 20 and couples to hydrogen storage14.

Hydrogen storage device 14 stores and outputs hydrogen, which may be apure source such as compressed hydrogen held in a pressurized container14. Hydrogen storage device 14 may also include a solid-hydrogen storagesystem such as a metal-based hydrogen storage device known to those ofskill in the art. An outlet of hydrogen storage device 14 detachablycouples to fuel cell 20 so that storage device 14 may be replaced whendepleted.

Fuel cell 20 electrochemically converts hydrogen and oxygen to water,generating electrical energy and heat in the process. Ambient aircommonly supplies oxygen for fuel cell 20. A pure or direct oxygensource may also be used for oxygen supply. The water often forms as avapor, depending on the temperature of fuel cell 20 components. For somefuel cells, the electrochemical reaction may also produce carbon dioxideas a byproduct.

In one embodiment, fuel cell 20 is a low volume ion conductive membrane(PEM) fuel cell suitable for use with portable applications such asconsumer electronics. An ion conductive membrane fuel cell comprises amembrane electrode assembly that carries out the electrical energygenerating electrochemical reaction. The membrane electrode assemblyincludes a hydrogen catalyst, an oxygen catalyst and an ion conductivemembrane that a) selectively conducts protons and b) electricallyisolates the hydrogen catalyst from the oxygen catalyst. A hydrogen gasdistribution layer contains the hydrogen catalyst and allows thediffusion of hydrogen therethrough. An oxygen gas distribution layercontains the oxygen catalyst and allows the diffusion of oxygen andhydrogen protons therethrough. The ion conductive membrane separates thehydrogen and oxygen gas distribution layers. In chemical terms, theanode comprises the hydrogen gas distribution layer and hydrogencatalyst, while the cathode comprises the oxygen gas distribution layerand oxygen catalyst.

In one embodiment, a PEM fuel cell includes a fuel cell stack having aset of bi-polar plates. A membrane electrode assembly is disposedbetween two bi-polar plates. Hydrogen distribution occurs via a channelfield on one plate while oxygen distribution occurs via a channel fieldon a second plate on the other side of the membrane electrode assembly.Specifically, a first channel field distributes hydrogen to the hydrogengas distribution layer, while a second channel field distributes oxygento the oxygen gas distribution layer. The term ‘bi-polar’ referselectrically to a bi-polar plate (whether comprised of one plate or twoplates) sandwiched between two membrane electrode assembly layers. Inthe stack, the bi-polar plate acts as both a negative terminal for oneadjacent (e.g., above) membrane electrode assembly and a positiveterminal for a second adjacent (e.g., below) membrane electrode assemblyarranged on the opposite face of the bi-polar plate.

In electrical terms, the anode includes the hydrogen gas distributionlayer, hydrogen catalyst and bi-polar plate. The anode acts as thenegative electrode for fuel cell 20 and conducts electrons that arefreed from hydrogen molecules so that they can be used externally, e.g.,to power an external circuit. In a fuel cell stack, the bi-polar platesare connected in series to add electrical potential gained in each layerof the stack. In electrical terms, the cathode includes the oxygen gasdistribution layer, oxygen catalyst and bi-polar plate. The cathoderepresents the positive electrode for fuel cell 20 and conducts theelectrons back from the external electrical circuit to the oxygencatalyst, where they can recombine with hydrogen ions and oxygen to formwater.

The hydrogen catalyst separates the hydrogen into protons and electrons.An ion conductive membrane blocks the electrons, and electricallyisolates the chemical anode (hydrogen gas distribution layer andhydrogen catalyst) from the chemical cathode. The ion conductivemembrane also selectively conducts positively charged ions.Electrically, the anode conducts electrons to a load (electrical energyis produced) or battery (energy is stored). Meanwhile, protons movethrough the ion conductive membrane. The protons and used electronssubsequently meet on the cathode side, and combine with oxygen to formwater. The oxygen catalyst in the oxygen gas distribution layerfacilitates this reaction. One common oxygen catalyst comprises platinumpowder very thinly coated onto a carbon paper or cloth. Many designsemploy a rough and porous catalyst to increase surface area of theplatinum exposed to the hydrogen and oxygen.

In one embodiment, fuel cell 20 comprises a set of bi-polar platesformed from a single plate. Each plate includes channel fields onopposite surfaces of the plate. The single bi-polar plate thus duallydistributes hydrogen and oxygen: one channel field distributes hydrogenwhile a channel field on the opposite surface distributes oxygen.Multiple bi-polar plates can be stacked to produce a ‘fuel cell stack’in which a membrane electrode assembly is disposed between each pair ofadjacent bi-polar plates.

Since the electrical generation process in fuel cell 20 is exothermic,fuel cell 20 may implement a thermal management system to dissipate heatfrom the fuel cell. Fuel cell 20 may also employ a number ofhumidification plates (HP) to manage moisture levels in the fuel cell.Further description of a fuel cell suitable for use with the presentinvention is included in commonly owned co-pending patent applicationSer. No. 10/877,824 entitled “Micro Fuel Cell Architecture”, which isincorporated by reference for all purposes.

While the present invention will mainly be discussed with respect to PEMfuel cells, it is understood that the present invention may be practicedwith other fuel cell architectures. The main difference between fuelcell architectures is the type of ion conductive membrane used. In oneembodiment, fuel cell 20 is phosphoric acid fuel cell that employsliquid phosphoric acid for ion exchange. Solid oxide fuel cells employ ahard, non-porous ceramic compound for ion exchange and may be suitablefor use with the present invention. Generally, any fuel cellarchitecture may be applicable to the space saving designs describedherein. Other such fuel cell architectures include direct methanol,alkaline and molten carbonate fuel cells, for example.

Fuel cell 20 generates dc voltage, which may be used in a wide varietyof applications. For example, electrical energy generated by fuel cell20 may power a motor or light. In one embodiment, the present inventionprovides ‘small’ fuel cells that are configured to output less than 200watts of power (net or total). Fuel cells of this size are commonlyreferred to as ‘micro fuel cells’ and are well suited for use withportable electronics devices. In one embodiment, fuel cell 20 isconfigured to generate from about 1 milliwatt to about 200 Watts. Inanother embodiment, fuel cell 20 generates from about 5 Watts to about60 Watts. Fuel cell 20 may be a stand-alone fuel cell, which is a singlepackage that produces power as long as it has access to a) oxygen and b)hydrogen or a hydrocarbon fuel supply. A stand-alone fuel cell 20 thatoutputs from about 10 Watts to about 100 Watts is well suited to power alaptop computer. One specific fuel cell package produces greater thanabout 10 Watts. Another specific fuel cell package produces greater thanabout 45 Watts.

A fuel cell package of the present invention may also use a ‘reformed’hydrogen supply. FIG. 1B illustrates a fuel cell package 10 forproducing electrical energy in accordance with another embodiment of thepresent invention. Fuel cell package 10 comprises a fuel processor 15and a fuel cell 20.

Processor 15 processes a fuel source 17 to produce hydrogen. Fuel source17 acts as a carrier for hydrogen and can be manipulated to separatehydrogen. Fuel source 17 may include any hydrogen bearing fuel stream,hydrocarbon fuel, or other hydrogen fuel source such as ammonia.Currently available hydrocarbon fuel sources 17 suitable for use withthe present invention include methanol, ethanol, gasoline, propane,butane and natural gas, for example. Liquid fuel sources 17 offer highenergy densities and the ability to be readily stored and shipped. Otherfuel sources may be used with a fuel cell package of the presentinvention, such as sodium borohydride. Several hydrocarbon and ammoniaproducts may also produce a suitable fuel source 17.

Fuel source 17 may be stored as a fuel mixture. When the fuel processor15 comprises a steam reformer, storage device 16 contains a fuel mixtureof a hydrocarbon fuel source and water. Hydrocarbon fuel source/waterfuel mixtures are frequently represented as a percentage fuel source inwater. In one embodiment, fuel source 17 comprises methanol or ethanolconcentrations in water in the range of 1%-99.9%. Other liquid fuelssuch as butane, propane, gasoline, military grade “JP8” etc. may also becontained in storage device 16 with concentrations in water from 5-100%.In a specific embodiment, fuel source 17 includes 67% methanol byvolume.

As shown, the reformed hydrogen supply comprises a fuel processor 15 anda fuel source storage device 16. Storage device 16 stores fuel source17, and may comprise a portable and/or disposable fuel cartridge. Adisposable cartridge offers a user instant recharging. In oneembodiment, the cartridge includes a collapsible bladder within a hardprotective case. A fuel pump typically moves fuel source 17 from storagedevice 16 to the processor 15. If package 10 is load following, then acontrol system meters fuel source 17 to deliver fuel source 17 toprocessor 15 at a flow rate determined by a desired power level outputof fuel cell 20.

Fuel processor 15 processes the hydrocarbon fuel source 17 and outputshydrogen. A hydrocarbon fuel processor 15 heats and processes ahydrocarbon fuel source 17 in the presence of a catalyst to producehydrogen. Fuel processor 15 comprises a reformer, which is a catalyticdevice that converts a liquid or gaseous hydrocarbon fuel source 17 intohydrogen and carbon dioxide. As the term is used herein, reformingrefers to the process of producing hydrogen from a fuel source. Onesuitable fuel processor 15 is described in further detail below.

In one embodiment, fuel processor 15 is a steam reformer that only needssteam and fuel to produce hydrogen. Several types of reformers suitablefor use in fuel cell package 10 include steam reformers, auto thermalreformers (ATR) or catalytic partial oxidizers (CPOX). ATR and CPOXreformers mix air with the fuel and steam mix. ATR and CPOX systemsreform fuels such as methanol, diesel, regular unleaded gasoline andother hydrocarbons. In a specific embodiment, storage device 16 providesmethanol 17 to fuel processor 15, which reforms the methanol at about280° C. or less and allows fuel cell package 10 use in applicationswhere temperature is to be minimized.

A fuel cell 20 may be configured to receive hydrogen from either adirect hydrogen supply 12 or a reformed source. Fuel cell 20 typicallyreceives hydrogen from one supply at a time, although fuel cell packagesthat employ redundant hydrogen provision from multiple supplies areuseful in some applications.

FIG. 1C illustrates schematic operation for the fuel cell package 10 ofFIG. 1B in accordance with a specific embodiment of the presentinvention. As shown, package 10 includes fuel processor 15, fuel cell20, multiple pumps 21, an air pump 41, various fuel conduits and gasconduits, and one or more valves 23. A fuel container 16 couples topackage 10 and stores a hydrogen fuel source 17 for supply to componentswithin package 10.

Fuel container 16 stores methanol as a hydrogen fuel source 17. Anoutlet 26 of fuel container 16 provides methanol 17 into hydrogen fuelsource conduit 25. As shown, conduit 25 divides into two conduits: afirst conduit 27 that transports methanol 17 to a heater (also referredto herein as a ‘burner’) 30 for fuel processor 15 and a second conduit29 that transports methanol 17 to a reformer 32 in fuel processor 15.Conduits 25, 27 and 29 may comprise channels disposed in the fuelprocessor or tubes leading thereto, for example. Separate pumps 21 a and21 b are provided for conduits 27 and 29, respectively, to pressurizethe conduits and transfer methanol at independent rates, if desired. Amodel 030SP-S6112 pump as provided by Biochem, NJ is suitable totransmit liquid methanol for system 10 is suitable in this embodiment.

In one embodiment, the pump is positive displacement and the system doesnot use a flow meter. In this case, the control system knows how muchfuel is being pumped, and the control system communicates thisinformation to a chip on the fuel cartridge. In another embodiment, aflow sensor or valve 23, situated between storage device 16 and fuelprocessor 18, detects and communicates the amount of methanol 17transfer between storage device 16 and reformer 32. In conjunction withthe sensor or valve 23 and suitable control, such as digital controlapplied by a processor that implements instructions from storedsoftware, pump 21 b regulates methanol 17 provision from storage device16 to reformer 32.

Air pump 41 delivers oxygen and air from the ambient room throughconduit 31 to the cathode in the fuel cell 20, where some oxygen is usedin the cathode to generate electricity. Air pump 41 may include a fan orcompressor, for example. High operating temperatures in fuel cell 20also heat the oxygen and air. In the embodiment shown, the heated oxygenand air is then transmitted via conduit 33 to regenerator 36 of fuelprocessor 15, where it is additionally heated before entering heater 30.This double pre-heating increases efficiency of the fuel cell system bya) reducing heat lost to reactants in heater 30 (such as fresh oxygenthat would otherwise be near room temperature), b) cooling the fuel cellduring energy production. In this embodiment, a model BTC compressor asprovided by Hargraves, NC is suitable to pressurize oxygen and air forfuel cell system 10.

A fan 37 blows cooling air (e.g. from the ambient room) over fuel cell20 and its heat transfer appendages 46. Fan 37 may be suitable sized tomove air as desired by heating requirements of the fuel cell; and manyvendors known to those of skill in the art provide fans suitable for usewith package 10. An additional fan may be used to blow air over a heatersection of the fuel cell heat transfer appendages.

Fuel processor 15 receives methanol 17 from storage device 16 andoutputs hydrogen. Fuel processor 15 comprises heater 30, reformer 32,boiler 34 and regenerator 36. Heater (or burner) 30 includes an inlet(which also functions as a boiler if methanol is present) that receivesmethanol 17 from conduit 27 and a catalyst that generates heat withmethanol presence. Boiler 34 includes an inlet that receives methanol 17from conduit 29. The structure of boiler 34 permits heat produced inheater 30 to heat methanol 17 in boiler 34 before reformer 32 receivesthe methanol 17. Boiler 34 includes an outlet that provides heatedmethanol 17 to reformer 32. Reformer 32 includes an inlet that receivesheated methanol 17 from boiler 34. A catalyst in reformer 32 reacts withthe methanol 17 and produces hydrogen and carbon dioxide (along withabout −0.2-5% CO and any un-reacted methanol and steam). This reactionis slightly endothermic and draws heat from heater 30. A hydrogen outletof reformer 32 outputs hydrogen to conduit 39. In one embodiment, fuelprocessor 15 also includes a preferential oxidizer that interceptsreformer 32 hydrogen exhaust and decreases the amount of carbon monoxidein the exhaust. The preferential oxidizer employs oxygen from an airinlet to the preferential oxidizer and a catalyst, such as ruthenium orplatinum, that is preferential to carbon monoxide over hydrogen.

Regenerator 36 pre-heats air before the air enters heater 30.Regenerator 36 also reduces heat loss from package 10 by heating airbefore it escapes fuel processor 15. In one sense, regenerator useswaste heat in fuel processor 15 to increase thermal management andthermal efficiency of the fuel processor. Specifically, waste heat fromheater 30 may be used to pre-heat incoming air provided to heater 30 toreduce heat transfer to the air in the heater so more heat transfers toreformer 32. The regenerator also functions as insulation for the fuelprocessor, by reducing the overall amount of heat loss of the reformer.

Conduit 39 transports hydrogen from fuel processor 15 to fuel cell 20.Gaseous delivery conduits 31, 33 and 39 may comprise channels in metal,as will be described below. A hydrogen flow sensor (not shown) may alsobe added on conduit 39 to detect and communicate the amount of hydrogenbeing delivered to fuel cell 20. In conjunction with the hydrogen flowsensor and suitable control, such as digital control applied by aprocessor that implements instructions from stored software, fuelprocessor 15 regulates hydrogen gas provision to fuel cell 20.

Fuel cell 20 includes a hydrogen inlet port that receives hydrogen fromconduit 39 and delivers it to a hydrogen intake manifold for delivery toone or more bi-polar plates and their hydrogen distribution channels. Anoxygen inlet port of fuel cell 20 receives oxygen from conduit 31 anddelivers it to an oxygen intake manifold for delivery to one or morebi-polar plates and their oxygen distribution channels. An anode exhaustmanifold 38 collects gases from the hydrogen distribution channels anddelivers them to the ambient room, or back to the fuel processor. Acathode exhaust manifold collects gases from the oxygen distributionchannels and delivers them to a cathode exhaust port and conduit 33, orto the ambient room.

In addition to the components shown in shown in FIG. 1C, system 10 mayalso include other elements such as electronic controls, additionalpumps and valves, added system sensors, manifolds, heat exchangers andelectrical interconnects useful for carrying out functionality of a fuelcell system 10 that are known to one of skill in the art and omittedherein for sake of brevity.

Package

The present invention provides a reduced-size and portable fuel cellpackage. As the term is used herein, a fuel package refers to a fuelcell system that receives hydrogen, or a hydrogen fuel source, andoutputs electrical energy. At a minimum, this includes a fuel cell. Thepackage need not include a cover or housing, e.g., in the case where afuel cell, or a fuel cell and fuel processor, is included in a batterybay of a laptop computer. In this case, the fuel cell package onlyincludes the fuel cell, or fuel cell and fuel processor, and no housing.The package may include a compact profile, low volume, or low mass—anyof which is useful in any power application where size is relevant. Asthe term is used herein, fuel cell package and fuel cell system aresynonymous, where package is used to more conveniently express volumeand power density.

In one embodiment, the fuel cell package includes a fuel cell, a fuelprocessor, and dedicated connectivity between the two. The dedicatedconnectivity may provide a) fluid or gas communication between the fuelprocessor and the fuel cell, and/or b) structural support between thetwo or for the package. In one embodiment, an interconnect as describedbelow provides much of the connectivity. In another embodiment, directand dedicated connectivity is provided on the fuel cell and/or fuelprocessor to interface with the other. For example, a fuel cell may bedesigned to interface with a particular fuel processor and includesdedicated connectivity for that fuel processor. Alternatively, a fuelprocessor may be designed to interface with a particular fuel cell.Assembling the fuel processor and fuel cell together in a common andsubstantially enclosed package provides a portable ‘black box’ packagethat receives a hydrogen fuel source and outputs electrical energy.

One or more conduits or channels communicate gases or fluids between thefuel cell and fuel processor. At the least, the communication includes aline that transports hydrogen to the fuel cell. To reduce package size,the fuel cell and the fuel processor may each include a molded channeldedicated to the delivering hydrogen from the processor to the cell. Thechanneling may be included in structure for each. When the fuel cellattaches directly to the fuel processor, the hydrogen transport linethen includes a) channeling in the fuel processor to deliver hydrogenfrom a reformer to the connection, and b) channeling in the fuel cell todeliver the hydrogen from the connection to a hydrogen intake manifold.An interconnect as described below may facilitate connection between thefuel cell and the fuel processor. In this case, the interconnectincludes an integrated hydrogen conduit dedicated to hydrogen transferfrom the fuel processor to the fuel cell.

FIG. 4A illustrates a fuel cell package 400 in accordance with oneembodiment of the present invention. Package 400 provides compact andportable electrical energy generation using fuel cell technology.

An outer housing 402 contains a fuel cell. Housing 402 providesmechanical protection for internal components within its boundaries, andmay include any shape or configuration to provide such protection. Inone embodiment, housing 402 includes multiple pieces secured togetherusing screws and/or a suitable adhesive. Materials used in housing 402may include any suitably stiff material that provides mechanicalprotection. For example, a rigid plastic or metal may be used forhousing 402. In one embodiment, housing 402 includes a low thermalconductance material so that the housing does not act as a heat sink forheat generation within its volume. In another embodiment, housing 402includes a thermally conductive material. In one embodiment, housing 402is dimensioned according to the internal components contained therein toreduce overall package volume.

Housing 402 includes a number of openings for air intake and exhaust.Opening 404 allows air from the ambient room or environment to enterpackage 400, e.g., to cool a fuel cell contained therein or for energygeneration in the fuel cell. Opening 406 acts as an exhaust port forheated gases after they acquire heat from the fuel cell, which typicallyoperates at an elevated temperature relative to air in the ambientenvironment. While openings 404 and 406 are shown as somewhat linearslits, the openings may comprise any dimensions suitable for intake andexhaust of cooling air (or oxygen used in a fuel processor). Inaddition, the package may include less or greater than two openings.

Not all fuel cell system components are necessarily included withinhousing 402. While housing 402 is useful to characterize volume, somepackages that resemble embedded systems do not include a housing 402.Alternatively, components that interface with a detachable hydrogen orfuel source storage device may be configured outside of housing 402. Atthe least, housing 402 at least partially contains the fuel cell. Thehousing 402 also usually contains the fuel processor, if one is includedin the system.

Volume may characterize package 400. The volume includes all componentsof the package used in the system to generate electricity, save astorage device used to supply hydrogen or a fuel source. In oneembodiment, the volume includes the fuel cell and any componentsexternal to housing 402 used to generate electricity (e.g., not justcomponents included within housing 402, such as a pump used for fueldelivery disposed partially outside the housing), and/or a powerconditioner that converts the fuel cell output voltage to a levelrequired by a power consumer and which may be turned on or off by thefuel cell control system as needed. In one embodiment, package 400 has atotal volume less than about a liter. In a specific embodiment, package400 has a total volume less than about ½ liter. Greater and lesserpackage volumes may be used with the present invention.

Package also includes a relatively small mass. In one embodiment,package 400 has a total mass less than about a 1 kg. In a specificembodiment, package 400 has a total volume less than about ½ liter.Greater and lesser package masses are possible.

Power density may also be used to characterize a fuel cell package.Power density refers to the ratio of electrical power output provided bya fuel cell included in the package relative to a physical parametersuch as volume or mass of the package. Notably, the present inventionprovides fuel cell packages with power densities not yet attained in thefuel cell industry. In one embodiment, fuel cell package 400 provides apower density of greater than about 30 Watts/liter. This packageincludes all balance of plant items (cooling system, power conversion,start-up battery, etc.) except the fuel and fuel source storage device.In another specific embodiment, fuel cell package 400 provides a powerdensity of greater than about 60 Watts/liter. A power density from about45 Watts/liter to about 90 Watts/liter works well for many portableapplications. Greater and lesser power densities are also permissiblewith a fuel cell package of the present invention.

A fuel cell and fuel processor may be arranged in a package so as tominimize package volume. In one embodiment, the fuel processor and fuelcell are arranged to be coplanar in the package. Coplanar in this senserefers to the shortest and/or longest dimension used to characterize thefuel cell and to characterize the fuel processor being aligned in thesame axis. The shortest dimension refers to the smallest dimension ofthree dimensions (e.g., x, y, z) used to characterize size of eithercomponent. The longest dimension conveys the opposite. For example, ifheight for both the fuel cell and fuel processor is the smallestdimension, then the fuel cell and fuel processor are placed adjacent andcoplanar to each other such that height for both is in a commondirection (e.g., z). The fuel cell and fuel processor may be arrangedbeside each other, stacked on top of each other, or in any otherarrangement that reduces volume. When arranged beside each other, heightof the taller of the two determines overall height of the package. Inone embodiment, the fuel cell system package has a height determined bythe fuel cell. In a specific embodiment, the fuel cell and package has aheight less than about 1 inch. Other heights are contemplated, such asless than about 2 inches, or the height of a battery slot in a laptopcomputer.

FIG. 4B shows a perspective view of a coplanar fuel cell system in asingle package 420 in accordance with one embodiment of the presentinvention. Package 420 includes fuel cell 20 and fuel processor 15,arranged adjacent to each other such that their heights aresubstantially parallel.

Fuel cell 20 is shown with a housing 422 that includes top plate 64 anda number of sidewalls 424. Sidewall 424 a includes two openings: acooling air intake 428 and an exhaust 430. Cooling fan 37 of FIG. 1C isdisposed relatively close and internal to intake 428 or exhaust 430.

For package 420, fuel pumps 21 are included for plumbing control andattached to an external housing of the package. Fuel pumps 21 may employa solenoid pump, syringe pump or any other commercially available pumpthat moves a fuel. FIG. 4B also shows an air intake pipe 432 (line 31 ofFIG. 1C) that communicates oxygen and air from the ambient room orenvironment, through the package housing, and to fuel cell 20 for use inthe cathode.

Orthogonal dimensions of length (L), width (W) and height (H)characterize package 420. In one embodiment, package 420 includes alength between about 6 cm and about 15 cm, a width between about 4 cmand about 10 cm, and a height between about 1 cm and about 5 cm. As oneof skill in the art will appreciate, package dimensions will depend onthe arrangement and size of fuel cell 20 and fuel processor 15, andwhether a fuel processor 15 is even included in the package. Exclusionof fuel processor 15 reduces dimensions for package 420 by thedimensions of the processor and its associated balance of plantrequirements. In a specific embodiment, package 420 includes a lengthbetween about 11 cm and about 13 cm, a width between about 7 cm andabout 9 cm, and a height between about 2 cm and about 4 cm. Greater andlesser dimensions may be used for a package of the present invention.

FIG. 4C illustrates a perspective view of internal components for a fuelcell package 440 in accordance with another embodiment of the presentinvention.

Package 440 includes a block chassis 442 that acts as a structuralframework to which functional components of package 440 are attached. Inone embodiment, chassis 442 forms a bottom wall of an external housingfor package 440. Chassis 442 includes a suitably stiff material, such asa metal or rigid plastic. Aluminum, Fr₄, carbon fiber, ABS and steel areall suitable for use. Alternatively, any material that providesmechanical integrity and includes a low thermal conductance may be used.

Package 440 also includes fluid conduits and connections 444incorporated into fuel cell 20 and fuel processor 15, as opposed toseparate tubes and hoses between the fuel cell 20 and processor 15. Thisdecreases size for package 440. Pump 21 provides fuel source movementand is coupled to a bracket that attaches to chassis 442. An aircompressor 448 provides air to the fuel cell cathode and is attached tochassis 442. An intake plenum 445 is included to guide air between anouter housing of package 440 and inlet port 428 of fuel cell 20.

Package 440 also includes a rechargeable battery 450 (not labeled ondrawing). In one embodiment, battery 450 is used during startup toprovide electrical power for heating fuel in fuel processor 15 until thefuel processor and fuel cell 20 are ready to generate electrical energy.Then, the rechargeable battery may be recharged by fuel cell 20. Ifrechargeable battery 450 is empty, the fuel cell system may employ a USBjumpstart (the battery can be charged by devices other than the fuelcell, and the system can be started by devices other than the systembattery). In this case, a USB connection between package 440 and anelectronics device such as a laptop computer provides power to chargethe system battery until it reaches a state of charge so that it canheat fuel for fuel processor 15 until fuel cell 20 generates electricalenergy. At this point, battery 450 may be recharged by the fuel cell. Awide variety of vendors known to those of skill in the art providerechargeable batteries suitable for use with the present invention. A2.4 Amp Hour 18650 rechargeable battery is suitable for someembodiments. A battery that provides 18 watts at 50% charge and 3.75volts is also suitable. Other commercially available batteries may beused.

Control board 452 includes suitable software and hardware forcontrolling components within package 440. Hardware may include acommercially available processor, such as any of those available in theIntel, MicroChip or Motorola family of processors. Some form of memoryis also included. Random-access memory (RAM) and read-only memory (ROM)may be included to store program instructions, implemented by theprocessor, that execute control functions for one more components of afuel cell system. The control board may also include a device to allowfor reprogramming of the control system firmware without the need toremove the control board.

An electrical adapter may also be included in the package (not shown inFIG. 4C, and can also be part of control board 452) converts electricalenergy output by fuel cell 20 to a suitable level as determined bydesign of package 440. For example, package 440 may be used as atethered adapter to power a laptop computer, in which electrical adapter446 converts electrical energy output by fuel cell 20 to a voltage andcurrent suitable for electrical provision to the laptop. DC/DCconversion is typical, but other power conditioning may also be applied.The electrical adaptor, or power regulator, may also have the capabilityto be turned on or off as needed, and may include load levelingcapabilities such as provided by capacitors on the input and outputlines. In one embodiment, the electrical adaptor has an electricalefficiency greater than about 90%. In a specific embodiment, theelectrical adaptor has an efficiency greater than about 95%. Otherdevices may be powered by fuel cell 20, and adapter 446 will beconfigured according to electrical requirements of the device. Adapter446 may also include a hardware interface that receives a wire thatcouples to the electronics device.

Package 440 may also includes additional fuel cell system componentssuch as a cathode air inlet 31, a fuel feed from a detachable fuelsource cartridge that couples to package 440, and a sensor and wires fortemperature sensing.

Although fuel cell packages have been largely described with respect tofuel processor inclusion, a package of the present invention need notinclude a processor. In another embodiment, the package only includes afuel cell that receives hydrogen from a supply coupled to the package.The package then provides a portable black box that receives hydrogenand outputs electrical energy. Since the volume has decreased, thisprovides fuel cell packages with less volume and mass—for the same poweroutput—and thus even greater power densities.

In one embodiment, the present invention provides a tethered fuel cellpackage. FIG. 7A shows a simplified illustration of a tethered fuel cellpackage 700 in accordance with one embodiment of the present invention.FIG. 7B illustrates an internal perspective view of tethered fuel cellpackage 700 in accordance with a specific embodiment of the presentinvention.

A tethered package refers to a fuel cell package including a tether 702.Tether 702 allows electrical coupling to the package from a distance,and typically includes a conductor capable of communicating electricalenergy from a fuel cell or electrical adapter included in the package700 to an electronics device. In one embodiment, tether 702 includes awire detachably coupled to package 700 and configured to transmit DCelectricity generated by the fuel cell. A connector 705 allows thetether to be electrically and detachably connected to an electricaladaptor 710 included in the package. Typically, a length of tether 702determines the tether distance, but adding an extension cord (or thelike) to either end may lengthen the tether distance. The tethered fuelcell package may resemble an AC adapter used for many conventionallaptop computers, where the tethered package provides electrical energyfrom stored hydrogen or a fuel source.

Since the fuel cell package is portable, tethering the package providesa portable form of electrical power that may be plugged into one ormultiple portable electronics devices. An output end 704 of the tetherincludes an interface 705 that electrically and detachably couples to anelectronics device, while a fuel cell end 706 electrically anddetachably couples to the fuel cell package (or is permanently attachedthereto). Interface 705 may include any suitable electronics interface.For example, interface 705 may include a DC adapter interface, such asany of those commercially available from a wide array of vendors.

Tethered fuel cell package 700 then provides a portable source ofelectrical power suitable to detachably power one or more devices. Forexample, consumer electronics devices such as laptop computers andradios may benefit from a tethered adapter of the present invention.Tethered fuel cell package 700 may power multiple models of the sametype, such as multiple computer laptops of the same model.

Tethered fuel cell package 700 may also provide varying electricaloutput to power different devices. Referring to FIG. 7B, package 700includes an electrical adaptor 710 that converts electrical energyoutput by fuel cell 20 to a different electrical level for output ontether 702. In one embodiment, adapter 710 provides multiple outputelectrical settings for package 700. For example, one setting mayinclude 12V 3 A service while a second provides 5V 1 A service. A switchor other device on the outside of the package 700 may allow a user tochange between the multiple electrical outputs. The connector may alsobe wired so that the control board knows as what output voltage itshould be operated. Electrical adapter 710 then includes suitableelectronics to service each output setting. In this case, adapter 710provides DC/DC conversion as determined by design of fuel cell 20 anddesired output using tether 702.

Adapter 710 may also provide AC/DC conversion. In this case, package 700includes a second connector (not shown) that receives an AC connector orwire. The AC wire detachably couples to an AC power source, such as awall socket. Adapter 710 then includes circuitry that converts AC powerinto DC output on tether 702. For example, the circuitry may convert 65Watt AC input into 45 Watt DC output.

Fuel Cell

FIG. 2A illustrates a cross sectional view of a fuel cell stack 60 foruse in fuel cell 20 in accordance with one embodiment of the presentinvention. FIG. 2B illustrates an outer top perspective view of a fuelcell stack 60 and fuel cell 20 in accordance with another embodiment ofthe present invention.

Referring initially to FIG. 2A, fuel cell stack 60 includes a set ofbi-polar plates 44 and a set of membrane electrode assembly (MEA) layers62. Two MEA layers 62 neighbor each bi-polar plate 44. With theexception of topmost and bottommost membrane electrode assembly layers62 a and 62 b, each MEA 62 is disposed between two adjacent bi-polarplates 44. For MEAs 62 a and 62 b, top and bottom end plates 64 a and 64b include a channel field 72 on the face neighboring an MEA 62.

The bi-polar plates 44 in stack 60 also each include one or more heattransfer appendages 46. As shown, each bi-polar plate 44 includes a heattransfer appendage 46 a on one side of the plate and a heat transferappendage 46 b on the opposite side. Heat transfer appendages 46 arediscussed in further detail below.

As shown in FIG. 2A, stack 60 includes twelve membrane electrodeassembly layers 62, eleven bi-polar plates 44 and two end plates 64(FIG. 2B shows 18 plates 44 in the stack). The number of bi-polar plates44 and MEA layers 62 in each set may vary with design of fuel cell stack60. Stacking parallel layers in fuel cell stack 60 permits efficient useof space and increased power density for fuel cell 20 and a fuel cellpackage 10 including fuel cell 20. In one embodiment, each membraneelectrode assembly 62 produces 0.7 V and the number of MEA layers 62 isselected to achieve a desired voltage. Alternatively, the number of MEAlayers 62 and bi-polar plates 44 may be determined by the allowablethickness of package 10. A fuel cell stack 60 having from one MEA 62 toseveral hundred MEAs 62 is suitable for many applications. A stack 60having from about three MEAs 62 to about twenty MEAs 62 is also suitablefor numerous applications. Fuel cell 20 size and layout may also betailored and configured to output a given power.

Referring to FIG. 2B, top and bottom end plates 64 a and 64 b providemechanical protection for stack 60. End plates 64 also hold the bi-polarplates 44 and MEA layers 62 together, and apply pressure across theplanar area of each bi-polar plate 44 and each MEA 62. End plates 64 mayinclude steel or another suitably stiff material. Bolts 82 a-d connectand secure top and bottom end plates 64 a and 64 b together.

Fuel cell 20 includes two anode manifolds (84 and 86). Each manifolddelivers a product or reactant gas to or from the fuel cell stack 60.More specifically, each manifold delivers a gas between a verticalmanifold created by stacking bi-polar plates 44 (FIG. 2D) and plumbingexternal to fuel cell 20. Inlet hydrogen manifold 84 is disposed on topend plate 64 a, couples with an inlet conduit to receive hydrogen gas(such as 204 a in FIG. 4A), and opens to an inlet hydrogen manifold 102(FIG. 2D) that is configured to deliver inlet hydrogen gas to a channelfield 72 on each bi-polar plate 44 in stack 60. Outlet manifold 86receives outlet gases from an anode exhaust manifold 104 (FIG. 2D) thatis configured to collect waste products from the anode channel fields 72of each bi-polar plate 44. Outlet manifold 86 may provide the exhaustgases to the ambient space about the fuel cell. In another embodiment,manifold 86 provides the anode exhaust to line 38, which transports theunused hydrogen back to the fuel processor during start-up.

Fuel cell 20 includes two cathode manifolds: an inlet cathode manifoldor inlet oxygen manifold 88, and an outlet cathode manifold or outletwater/vapor manifold 90. Inlet oxygen manifold 88 is disposed on top endplate 64 a, couples with an inlet conduit (conduit 31, which draws airfrom the ambient room) to receive ambient air, and opens to an oxygenmanifold 106 (FIG. 2D) that is configured to deliver inlet oxygen andambient air to a channel field 72 on each bi-polar plate 44 in stack 60.Outlet water/vapor manifold 90 receives outlet gases from a cathodeexhaust manifold 108 (FIG. 2D) that is configured to collect water(typically as a vapor) from the cathode channel fields 72 on eachbi-polar plate 44.

As shown in FIG. 2B, manifolds 84, 86, 88 and 90 include molded channelsthat each travel along a top surface of end plate 64 a from theirinterface from outside the fuel cell to a manifold in the stack. Eachmanifold or channel acts as a gaseous communication line for fuel cell20 and may comprise a molded channel in plate 64 or a housing of fuelcell 20. Other arrangements to communicate gases to and from stack 60are contemplated, such as those that do not share common manifolding ina single plate or structure.

FIG. 2C illustrates an ion conductive membrane fuel cell (PEMFC)architecture 120 for use in fuel cell 20 in accordance with oneembodiment of the present invention. As shown, PEMFC architecture 120comprises two bi-polar plates 44 and a membrane electrode assembly layer(or MEA) 62 sandwiched between the two bi-polar plates 44. The MEA 62electrochemically converts hydrogen and oxygen to water and generateselectrical energy and heat in the process. Membrane electrode assembly62 includes an anode gas diffusion layer 122, a cathode gas diffusionlayer 124, a hydrogen catalyst 126, ion conductive membrane 128, anodeelectrode 130, cathode electrode 132, and oxygen catalyst 134.

Pressurized hydrogen gas (H₂) enters fuel cell 20 via hydrogen port 84,proceeds through inlet hydrogen manifold 102 and through hydrogenchannels 74 of a hydrogen channel field 72 a disposed on the anode face75 of bi-polar plate 44 a. The hydrogen channels 74 open to anode gasdiffusion layer 122, which is disposed between the anode face 75 ofbi-polar plate 44 a and ion conductive membrane 128. The pressure forceshydrogen gas into the hydrogen-permeable anode gas diffusion layer 122and across the hydrogen catalyst 126, which is disposed in the anode gasdiffusion layer 122. When an H₂ molecule contacts hydrogen catalyst 126,it splits into two H+ ions (protons) and two electrons (e−). The protonsmove through the ion conductive membrane 128 to combine with oxygen incathode gas diffusion layer 124. The electrons conduct through the anodeelectrode 130, where they build potential for use in an external circuit(e.g., a power supply of a laptop computer) After external use, theelectrons flow to the cathode electrode 132 of PEMFC architecture 120.

Hydrogen catalyst 126 breaks hydrogen into protons and electrons.Suitable catalysts 126 include platinum, ruthenium, and platinum blackor platinum carbon, and/or platinum on carbon nanotubes, for example.Anode gas diffusion layer 122 comprises any material that allows thediffusion of hydrogen therethrough and is capable of holding thehydrogen catalyst 126 to allow interaction between the catalyst andhydrogen molecules. One such suitable layer comprises a woven ornon-woven carbon paper. Other suitable gas diffusion layer 122 materialsmay comprise a silicon carbide matrix and a mixture of a woven ornon-woven carbon paper and Teflon.

On the cathode side of PEMFC architecture 120, pressurized air carryingoxygen gas (O₂) enters fuel cell 20 via oxygen port 88, proceeds throughinlet oxygen manifold 106, and through oxygen channels 76 of an oxygenchannel field 72 b disposed on the cathode face 77 of bi-polar plate 44b. The oxygen channels 76 open to cathode gas diffusion layer 124, whichis disposed between the cathode face 77 of bi-polar plate 44 b and ionconductive membrane 128. The pressure forces oxygen into cathode gasdiffusion layer 124 and across the oxygen catalyst 134 disposed in thecathode gas diffusion layer 124. When an O₂ molecule contacts oxygencatalyst 134, it splits into two oxygen atoms. Two H+ ions that havetraveled through the ion selective ion conductive membrane 128 and anoxygen atom combine with two electrons returning from the externalcircuit to form a water molecule (H₂O). Cathode channels 76 exhaust thewater, which usually forms as a vapor. This reaction in a single MEAlayer 62 produces about 0.7 volts.

Cathode gas diffusion layer 124 comprises a material that permitsdiffusion of oxygen and hydrogen protons therethrough and is capable ofholding the oxygen catalyst 134 to allow interaction between thecatalyst 134 with oxygen and hydrogen. Suitable gas diffusion layers 124may comprise carbon paper or cloth, for example. Other suitable gasdiffusion layer 124 materials may comprise a silicon carbide matrix anda mixture of a woven or non-woven carbon paper and Teflon. Oxygencatalyst 134 facilitates the reaction of oxygen and hydrogen to formwater. One common catalyst 134 comprises platinum. Many designs employ arough and porous catalyst 134 to increase surface area of catalyst 134exposed to the hydrogen or oxygen. For example, the platinum may resideas a powder very thinly coated onto a carbon paper or cloth cathode gasdiffusion layer 124.

Ion conductive membrane 128 electrically isolates the anode from thecathode by blocking electrons from passing through membrane 128. Thus,membrane 128 prevents the passage of electrons between gas diffusionlayer 122 and gas diffusion layer 124. Ion conductive membrane 128 alsoselectively conducts positively charged ions, e.g., hydrogen protonsfrom gas diffusion layer 122 to gas diffusion layer 124. For fuel cell20, protons move through membrane 128 and electrons are conducted awayto an electrical load or battery. In one embodiment, ion conductivemembrane 128 comprises an electrolyte. One electrolyte suitable for usewith fuel cell 20 is Celtec 1000 from PEMEAS USA AG of Murray Hill, N.J.(www.pemeas.com). Fuel cells 20 including this electrolyte are generallymore carbon monoxide tolerant and may not require humidification. Ionconductive membrane 128 may also employ a phosphoric acid matrix thatincludes a porous separator impregnated with phosphoric acid.Alternative ion conductive membranes 128 suitable for use with fuel cell20 are widely available from companies such as United technologies,DuPont, 3M, and other manufacturers known to those of skill in the art.For example, WL Gore Associates of Elkton, Md. produces the primeaSeries 58, which is a low temperature MEA suitable for use with thepresent invention.

In one embodiment, fuel cell 20 requires no external humidifier or heatexchanger and the stack 60 only needs hydrogen and air to produceelectrical power. Alternatively, fuel cell 20 may employ humidificationof the cathode to fuel cell 20 improve performance. For some fuel cellstack 60 designs, humidifying the cathode increases the power andoperating life of fuel cell 20.

FIG. 2D illustrates a top perspective view of a stack of bi-polar plates(with the top two plates labeled 44 p and 44 q) in accordance with oneembodiment of the present invention. Bi-polar plate 44 is a single plate44 with first channel fields 72 disposed on opposite faces 75 of theplate 44.

Functionally, bi-polar plate 44 a) delivers and distributes reactantgases to the gas diffusion layers 122 and 124 and their respectivecatalysts, b) maintains separation of the reactant gasses from oneanother between MEA layers 62 in stack 60, c) exhausts electrochemicalreaction byproducts from MEA layers 62, d) facilitates heat transfer toand/or from MEA layers 62 and fuel cell stack 60, and e) includes gasintake and gas exhaust manifolds for gas delivery to other bi-polarplates 44 in the fuel stack 60.

Structurally, bi-polar plate 44 has a relatively flat profile andincludes opposing top and bottom faces 75 a and 75 b (only top face 75 ais shown) and a number of sides 78. Faces 75 are substantially planarwith the exception of channels 76 formed as troughs into substrate 89.Sides 78 comprise portions of bi-polar plate 44 proximate to edges ofbi-polar plate 44 between the two faces 75. As shown, bi-polar plate 44is roughly quadrilateral with features for the intake manifolds, exhaustmanifolds and heat transfer appendage 46 that provide outer deviationfrom a quadrilateral shape.

The manifold on each plate 44 is configured to deliver a gas to achannel field on a face of the plate 44 or receive a gas from thechannel field 72. The manifolds for bi-polar plate 44 include aperturesor holes in substrate 89 that, when combined with manifolds of otherplates 44 in a stack 60, form an inter-plate 44 gaseous communicationmanifold (such as 102, 104, 106 and 108). Thus, when plates 44 arestacked and their manifolds substantially align, the manifolds permitgaseous delivery to and from each plate 44.

Bi-polar plate 44 includes a channel field 72 or “flow field” on eachface of plate 44. Each channel field 72 includes one or more channels 76formed into the substrate 89 of plate 44 such that the channel restsbelow the surface of plate 44. Each channel field 72 distributes one ormore reactant gasses to an active area for the fuel cell stack 60.Bi-polar plate 44 includes a first channel field 72 a on the anode face75 a of bi-polar plate 44 that distributes hydrogen to an anode (FIG.2C), while a second channel field on opposite cathode face 75 bdistributes oxygen to a cathode. Specifically, channel field 72 aincludes multiple channels 76 that permit oxygen and air flow to anodegas diffusion layer 122, while channel field 72 b includes multiplechannels 76 that permit oxygen and air flow to cathode gas diffusionlayer 124. For fuel cell stack 60, each channel field 72 is configuredto receive a reactant gas from an intake manifold 102 or 106 andconfigured to distribute the reactant gas to a gas diffusion layer 122or 124. Each channel field 72 also collects reaction byproducts forexhaust from fuel cell 20. When bi-polar plates 44 are stacked togetherin fuel cell 60, adjacent plates 44 sandwich an MEA layer 62 such thatthe anode face 75 a from one bi-polar plate 44 neighbors a cathode face75 b of an adjacent bi-polar plate 44 on an opposite side of the MEAlayer 62.

Bi-polar plate 44 may include one or more heat transfer appendages 46.Each heat transfer appendage 46 permits external thermal management ofinternal portions of fuel cell stack 60. More specifically, appendage 46may be used to heat or cool internal portions of fuel cell stack 60 suchas internal portions of each attached bi-polar plate 44 and anyneighboring MEA layers 62, for example. Heat transfer appendage 46 islaterally arranged outside channel field 72. In one embodiment,appendage 46 is disposed on an external portion of bi-polar plate 44.External portions of bi-polar plate 44 include any portions of plate 44proximate to a side or edge of the substrate included in plate 44.External portions of bi-polar plate 44 typically do not include achannel field 72. For the embodiment shown, heat transfer appendage 46substantially spans a side of plate 44 that does not include intake andoutput manifolds 102-108. For the embodiment shown in FIG. 2A, plate 44includes two heat transfer appendages 46 that substantially span bothsides of plate 44 that do not include a gas manifold.

Peripherally disposing heat transfer appendage 46 allows heat transferbetween inner portions of plate 44 and the externally disposed appendage46 via the plate substrate 89. Conductive thermal communication refersto heat transfer between bodies that are in contact or that areintegrally formed. Thus, lateral conduction of heat between externalportions of plate 44 (where the heat transfer appendage 46 attaches) andcentral portions of bi-polar plate 44 occurs via conductive thermalcommunication through substrate 89. In one embodiment, heat transferappendage 46 is integral with substrate material 89 in plate 44.Integral in this sense refers to material continuity between appendage46 and plate 44. An integrally formed appendage 46 may be formed withplate 44 in a single molding, stamping, machining or MEMs process of asingle metal sheet, for example. Integrally forming appendage 46 andplate 44 permits conductive thermal communication and heat transferbetween inner portions of plate 44 and the heat transfer appendage 46via substrate 89. In another embodiment, appendage 46 comprises amaterial other than that used in substrate 89 that is attached ontoplate 44 and conductive thermal communication and heat transfer occursat the junction of attachment between the two attached materials.

Heat may travel to or form the heat transfer appendage 46. In otherwords, appendage 46 may be employed as a heat sink or source. Thus, heattransfer appendage 46 may be used as a heat sink to cool internalportions of bi-polar plate 44 or an MEA 62. Fuel cell 20 employs acooling medium to remove heat from appendage 46. Alternatively, heattransfer appendage 46 may be employed as a heat source to provide heatto internal portions of bi-polar plate 44 or an MEA 62. In this case, acatalyst may be disposed on appendage 46 to generate heat in response tothe presence of a heating medium.

For cooling, heat transfer appendage 46 permits integral conductive heattransfer from inner portions of plate 44 to the externally disposedappendage 46. During hydrogen consumption and electrical energyproduction, the electrochemical reaction generates heat in each MEA 62.Since internal portions of bi-polar plate 44 are in contact with the MEA62, a heat transfer appendage 46 on a bi-polar plate 44 thus cools anMEA 62 adjacent to the plate via a) conductive heat transfer from MEA 62to bi-polar plate 44 and b) lateral thermal communication and conductiveheat transfer from central portions of the bi-polar plate 44 in contactwith the MEA 62 to the external portions of plate 44 that includeappendage 46. In this case, heat transfer appendage 46 sinks heat fromsubstrate 89 between a first channel field 72 on one face 75 of plate 44and a second channel field 72 on the opposite face of plate 44 to heattransfer appendage 46 in a direction parallel to a face 75 of plate 44.When a fuel cell stack 60 includes multiple MEA layers 62, lateralthermal communication through each bi-polar plate 44 in this mannerprovides interlayer cooling of multiple MEA layers 62 in stack60—including those layers in central portions of stack 60.

Fuel cell 20 may employ a cooling medium that passes over heat transferappendage 46. The cooling medium receives heat from appendage 46 andremoves the heat from fuel cell 20. Heat generated internal to stack 60thus conducts through bi-polar plate 44, to appendage 46, and heats thecooling medium via convective heat transfer between the appendage 46 andcooling medium. Air is suitable for use as the cooling medium.

Heat transfer appendage 46 may be configured with a thickness that isless than the thickness between opposite faces 75 of plate 44. Thereduced thickness of appendages 46 on adjacent bi-polar plates 44 in thefuel cell stack 60 forms a channel between adjacent appendages. Multipleadjacent bi-polar plates 44 and appendages 46 in stack form numerouschannels. Each channel permits a cooling medium or heating medium topass therethrough and across heat transfer appendages 46. In oneembodiment, fuel cell stack 60 includes a mechanical housing thatencloses and protects stack 60. Walls of the housing also provideadditional ducting for the cooling or heating medium by forming ductsbetween adjacent appendages 46 and the walls.

The cooling medium may be a gas or liquid. Heat transfer advantagesgained by high conductance bi-polar plates 44 allow air to be used as acooling medium to cool heat transfer appendages 46 and stack 60. Forexample, a dc-fan 37 may be attached to an external surface of themechanical housing. The fan 37 moves air through a hole in themechanical housing, through the channels between appendages to cool heattransfer appendages 46 and fuel cell stack 60, and out an exhaust holeor port in the mechanical housing. Fuel cell system 10 may then includeactive thermal controls based on temperature sensed feedback. Increasingor decreasing coolant fan speed regulates the amount of heat removalfrom stack 60 and the operating temperature for stack 60. In oneembodiment of an air-cooled stack 60, the coolant fan speed increases ordecreases as a function of the actual cathode exit temperature, relativeto a desired temperature set-point.

For heating, heat transfer appendage 46 allows integral heat transferfrom the externally disposed appendage 46 to inner portions of plate 44and any components and portions of fuel cell 20 in thermal communicationwith inner portions of plate 44. A heating medium passed over the heattransfer appendage 46 provides heat to the appendage. Heat convectedonto the appendage 46 then conducts through the substrate 89 and intointernal portions of plate 44 and stack 60, such as portions of MEA 62and its constituent components.

In one embodiment, the heating medium comprises a heated gas having atemperature greater than that of appendage 46. Exhaust gases from heater30 or reformer 32 of fuel processor 15 may each include elevatedtemperatures that are suitable for heating one or more appendages 46.

In another embodiment, fuel cell comprises a catalyst 192 (FIG. 2A)disposed in contact with, or in proximity to, one or more heat transferappendages 46. The catalyst 192 generates heat when the heating mediumpasses over it. The heating medium in this case may comprise any gas orfluid that reacts with catalyst 192 to generate heat. Typically,catalyst 192 and the heating medium employ an exothermic chemicalreaction to generate the heat. Heat transfer appendage 46 and plate 44then transfer heat into the fuel cell stack 60, e.g. to heat internalMEA layers 62. For example, catalyst 192 may comprise platinum and theheating medium includes the hydrocarbon fuel source 17. The fuel source17 may be heated to a gaseous state before it enters fuel cell 20. Thisallows gaseous transportation of the heating medium and gaseousinteraction between the fuel source 17 and catalyst 192 to generateheat. Similar to the cooling medium described above, a fan disposed onone of the walls then moves the gaseous heating medium within fuel cell20.

In a specific embodiment, the hydrocarbon fuel source 17 used to reactwith catalyst 192 comes from a reformer exhaust (see FIG. 1C) or heaterexhaust in fuel processor 15. This advantageously pre-heats the fuelsource 17 before receipt within fuel cell 20 and also efficiently usesor burns any fuel remaining in the reformer or heater exhaust afterprocessing by fuel processor 15. Alternatively, fuel cell 20 may includea separate hydrocarbon fuel source 17 feed that directly supplieshydrocarbon fuel source 17 to fuel cell 20 for heating and reaction withcatalyst 192. In this case, catalyst 192 may comprise platinum. Othersuitable catalysts 192 include palladium, a platinum/palladium mix,iron, ruthenium, and combinations thereof. Each of these will react witha hydrocarbon fuel source 17 to generate heat. Other suitable heatingmediums include hydrogen or any heated gases emitted from fuel processor15, for example.

When hydrogen is used as the heating medium, catalyst 192 comprises amaterial that generates heat in the presence of hydrogen, such aspalladium or platinum. As will be described in further detail below, thehydrogen may include hydrogen supplied from the reformer 32 in fuelprocessor 15 as exhaust.

As shown in FIG. 2A, catalyst 192 is arranged on, and in contact with,each heat transfer appendage 46. In this case, the heating medium passesover each appendage 46 and reacts with catalyst 192. This generatesheat, which is absorbed via conductive thermal communication by thecooler appendage 46. Wash coating may be employed to dispose catalyst192 on each appendage 46. A ceramic support may also be used to bondcatalyst 192 on an appendage 46.

For catalyst-based heating, heat then a) transfers from catalyst 192 toappendage 46, b) moves laterally though bi-polar plate 44 via conductiveheat transfer from lateral portions of the plate that include heattransfer appendage 46 to central portions of bi-polar plate 44 incontact with the MEA layers 62, and c) conducts from bi-polar plate 44to MEA layer 62. When a fuel cell stack 60 includes multiple MEA layers62, lateral heating through each bi-polar plate 44 provides interlayerheating of multiple MEA layers 62 in stack 60, which expedites fuel cell20 warm up.

Bi-polar plates 44 of FIG. 2A include heat transfer appendages 46 oneach side. In this case, one set of heat transfer appendages 46 a isused for cooling while the other set of heat transfer appendages 46 b isused for heating. Bi-polar plates 44 illustrated in FIG. 2D show plates44 with four heat transfer appendages 46 disposed on three sides ofstack 60. Appendage 46 arrangements can be otherwise varied to affectand improve heat dissipation and thermal management of fuel cell stack60 according to other specific designs. For example, appendages 46 neednot span a side of plate 44 as shown and may be tailored based on howthe heating fluid is channeled through the housing.

Although the present invention provides a bi-polar plate 44 havingchannel fields 72 that distribute hydrogen and oxygen on opposing sidesof a single plate 44, many embodiments described herein are suitable foruse with conventional bi-polar plate assemblies that employ two separateplates for distribution of hydrogen and oxygen.

While the present invention has mainly been discussed so far withrespect to a reformed methanol fuel cell (RMFC), the present inventionmay also apply to other types of fuel cells, such as a solid oxide fuelcell (SOFC), a phosphoric acid fuel cell (PAFC), a direct methanol fuelcell (DMFC), or a direct ethanol fuel cell (DEFC). In this case, fuelcell 20 includes components specific to these architectures, as one ofskill in the art will appreciate. A DMFC or DEFC receives and processesa fuel. More specifically, a DMFC or DEFC receives liquid methanol orethanol, respectively, channels the fuel into the fuel cell stack 60 andprocesses the liquid fuel to separate hydrogen for electrical energygeneration. For a DMFC, channel fields 72 in the bi-polar plates 44distribute liquid methanol instead of hydrogen. Hydrogen catalyst 126described above would then comprise a suitable anode catalyst forseparating hydrogen from methanol. Oxygen catalyst 128 would comprise asuitable cathode catalyst for processing oxygen or another suitableoxidant used in the DMFC, such as peroxide. In general, hydrogencatalyst 126 is also commonly referred to as an anode catalyst in otherfuel cell architectures and may comprise any suitable catalyst thatremoves hydrogen for electrical energy generation in a fuel cell, suchas directly from the fuel as in a DMFC. In general, oxygen catalyst 128may include any catalyst that processes an oxidant in used in fuel cell20. The oxidant may include any liquid or gas that oxidizes the fuel andis not limited to oxygen gas as described above. An SOFC, PAFC or MCFCmay also benefit from inventions described herein, for example. In thiscase, fuel cell 20 comprises an anode catalyst 126, cathode catalyst128, anode fuel and oxidant according to a specific SOFC, PAFC or MCFCdesign.

Fuel Processor

FIG. 3A illustrates a perspective view of components included in a fuelprocessor 15 in accordance with one embodiment of the present invention.FIG. 3B illustrates a cross-sectional front view of monolithic structure100. Fuel processor 15 reforms methanol to produce hydrogen. Fuelprocessor 15 comprises monolithic structure 100, end plates 182 and 184,end plate 185, reformer 32, heater 30, boiler 34, boiler 108, dewar 150and housing 152. Although the present invention will now be describedwith respect to methanol consumption for hydrogen production, it isunderstood that fuel processors of the present invention may consumeanother fuel source, as one of skill in the art will appreciate.

As the term is used herein, ‘monolithic’ refers to a single andintegrated structure that includes at least portions multiple componentsused in fuel processor 15. As shown in FIG. 3B, monolithic structure 100includes reformer 32, burner 30, boiler 34 and boiler 108. Monolithicstructure 100 also includes associated plumbing inlets and outlets forreformer 32, burner 30 and boiler 34 disposed on end plates 182 and 184and interconnect 200. Monolithic structure 100 comprises a commonmaterial 141 that constitutes the structure. The monolithic structure100 and common material 141 simplify manufacture of fuel processor 15.For example, using a metal for common material 141 allows monolithicstructure 100 to be formed by extrusion. In a specific embodiment,monolithic structure 100 is consistent in cross sectional dimensionsbetween end plates 182 and 184 and solely comprises copper formed in asingle extrusion.

Referring to FIG. 3B, housing 152 provides mechanical protection forinternal components of fuel processor 15 such as burner 30 and reformer32. Housing 152 also provides separation from the environment externalto processor 15 and includes inlet and outlet ports for gaseous andliquid communication in and out of fuel processor 15. Housing 152includes a set of housing walls that at least partially contain a dewar150 and provide external mechanical protection for components in fuelprocessor 15. The walls may comprises a suitably stiff material such asa metal or a rigid polymer, for example. Dewar 150 improves thermal heatmanagement for fuel processor 15 by a) allowing incoming air to bepre-heated before entering burner 30, b) dissipating heat generated byburner 32 into the incoming air before the heat reaches the outside ofhousing 152.

Boiler 34 heats methanol before reformer 32 receives the methanol.Boiler 34 receives methanol via a fuel source inlet 81 on interconnect200 (FIG. 5A), which couples to a methanol supply line 27 (FIG. 1C).Since methanol reforming and hydrogen production via a catalyst 102 inreformer 32 often requires elevated methanol temperatures, fuelprocessor 15 pre-heats the methanol before receipt by reformer 32 viaboiler 34. Boiler 34 is disposed in proximity to burner 30 to receiveheat generated in burner 30. The heat transfers via conduction throughmonolithic structure from burner 30 to boiler 34 and via convection fromboiler 34 walls to the methanol passing therethrough. In one embodiment,boiler 34 is configured to vaporize liquid methanol. Boiler 34 thenpasses the gaseous methanol to reformer 32 for gaseous interaction withcatalyst 102.

Reformer 32 is configured to receive methanol from boiler 34. Walls 111in monolithic structure 100 and end walls 113 on end plates 182 and 184define dimensions for a reformer chamber 103. In one embodiment, endplate 182 and/or end plate 184 includes a channel that routes heatedmethanol exhausted from boiler 34 into reformer 32.

In one embodiment, a reformer includes a multi-pass arrangement.Reformer 32 includes three multi-pass portions that process methanol inseries: chamber section 32 a, chamber section 32 b, and chamber section32 c. A reformer chamber 103 then includes the volume of all threesections 32 a-c. Each section traverses the length of monolithicstructure 100; and opens to each other in series such that sections 32a-c form one continuous path for gaseous flow. More specifically, heatedand gaseous methanol from boiler 34 a) enters reformer chamber section32 a at an inlet end of monolithic structure 100 and flows to the otherend over catalyst 102 in section 32 a, b) then flows into chambersection 32 b at the second end of monolithic structure 100 and flows tothe inlet end over catalyst 102 in section 32 b, and c) flows intochamber section 32 c at one end of monolithic structure 100 and flows tothe other end over catalyst 102 in the chamber section 32 c.

Reformer 32 includes a catalyst 102 that facilitates the production ofhydrogen. Catalyst 102 reacts with methanol and produces hydrogen gasand carbon dioxide. In one embodiment, catalyst 102 comprises pelletspacked to form a porous bed or otherwise suitably filled into the volumeof reformer chamber 103. Pellet diameters ranging from about 50 micronsto about 1.5 millimeters are suitable for many applications. Pelletdiameters ranging from about 500 microns to about 1 millimeter aresuitable for use with reformer 32. Pellet sizes may be varied relativeto the cross sectional size of reformer sections 32 a-c, e.g., as thereformer sections increase in size so does catalyst 102 pelletdiameters. Pellet sizes and packing may also be varied to control thepressure drop that occurs through reformer chamber 103. In oneembodiment, pressure drops from about 0.2 to about 2 psi gauge aresuitable between the inlet and outlet of reformer chamber 103. Onesuitable catalyst 102 may include CuZn coated onto alumina pellets whenmethanol is used as a hydrocarbon fuel source 17. Other materialssuitable for catalyst 102 include platinum, palladium, aplatinum/palladium mix, nickel, and other precious metal catalysts forexample. Catalyst 102 pellets are commercially available from a numberof vendors known to those of skill in the art. Catalyst 102 may alsocomprise catalyst materials listed above coated onto a metal sponge ormetal foam. A wash coat of the desired metal catalyst material onto thewalls of reformer chamber 103 may also be used for reformer 32.

Reformer 32 is configured to output hydrogen and includes an outlet port209 that communicates hydrogen formed in reformer 32 outside of fuelprocessor 15. Port 209 is disposed on a wall of end plate 184 andincludes a hole that passes through the wall. Port 209 opens to hydrogenconduit 204 a in interconnect 200, which then forms part of a hydrogenprovision line 39 (FIG. 1C). Line 39 communicates the hydrogen to theanode of fuel cell 20 for electrical energy generation.

Hydrogen production in reformer 32 is slightly endothermic and drawsheat from burner 30. Burner 30 generates heat and is configured toprovide heat to reformer 32. As shown in FIG. 3B, burner 30 comprisesfour burner chambers 105 a-d that surround reformer 32. In oneembodiment, burner 30 uses electrical resistance and electrical energyto produce heat.

In the embodiment shown, burner 30 employs catalytic combustion toproduce heat. As the term is used herein, a burner refers to a heaterthat uses a catalytic heating process to generate heat. A heater in afuel processor of the present invention may alternatively employelectrical heating, for example. A catalyst 104 disposed in each burnerchamber 105 helps a burner fuel passed through the chamber generateheat. Burner 30 includes an inlet that receives methanol 17 from boiler108 via a channel in one of end plates 182 or 184. In one embodiment,methanol produces heat in burner 30 and catalyst 104 facilitates themethanol production of heat. In another embodiment, waste hydrogen fromfuel cell 20 produces heat in the presence of catalyst 104. Suitableburner catalysts 104 may include platinum or palladium coated ontoalumina pellets for example. Other materials suitable for catalyst 104include iron, tin oxide, other noble-metal catalysts, reducible oxides,and mixtures thereof. The catalyst 104 is commercially available from anumber of vendors known to those of skill in the art as small pellets.The pellets that may be packed into burner chamber 105 to form a porousbed or otherwise suitably filled into the burner chamber volume.Catalyst 104 pellet sizes may be varied relative to the cross sectionalsize of burner chamber 105. Catalyst 104 may also comprise catalystmaterials listed above coated onto a metal sponge or metal foam or washcoated onto the walls of burner chamber 105.

Some fuel sources generate additional heat in burner 30, or generateheat more efficiently, with elevated temperatures. Fuel processor 15includes a boiler 108 that heats methanol before burner 30 receives thefuel source. In this case, boiler 108 receives the methanol via fuelsource inlet 85. Boiler 108 is disposed in proximity to burner 30 toreceive heat generated in burner 30. The heat transfers via conductionthrough monolithic structure from burner 30 to boiler 108 and viaconvection from boiler 108 walls to the methanol passing therethrough.

Air including oxygen enters fuel processor 15 via air inlet port 91.Burner 30 uses the oxygen for catalytic combustion of methanol. A burner30 in fuel processor 15 generates heat and typically operates at anelevated temperature. In one embodiment, fuel processor 15 comprises adewar 150 to improve thermal management for fuel processor 15. Dewar 150at least partially thermally isolates components internal to housing152—such as burner 30—and contains heat within fuel processor 15. Dewar150 is configured such that air passing through dewar chamber 156receives heat generated in burner 30. Dewar 150 offers thus twofunctions for fuel processor 15: a) it permits active cooling ofcomponents within fuel processor 15 before the heat reaches an outerportion of the fuel processor, and b) it pre-heats the air going toburner 30. Air first passes along the outside of dewar 150 beforepassing through apertures in the dewar and along the inside of dewar150. This heats the air before receipt by air inlet port 93 of burner30.

In one embodiment, package 10 runs anode exhaust from the fuel cell 20back to fuel processor. As shown in FIG. 1C, line 38 routes unusedhydrogen from fuel cell 20 burner inlet 109, which provides the anodeexhaust to burner 30 (or to the regenerator 36 and then to burner inlet109 and into burner 30). Burner 30 includes a thermal catalyst thatreacts with the unused hydrogen to produce heat. Since hydrogenconsumption within fuel cell 20 is often incomplete and the anodeexhaust often includes unused hydrogen, re-routing the anode exhaust toburner 30 allows fuel cell system 10 to capitalize on unused hydrogen infuel cell 20 and increase hydrogen usage and efficiency. Package 10 thusprovides flexibility to use different fuels in a catalytic burner 30.For example, if fuel cell 20 can reliably and efficiently consume over90% of the hydrogen in the anode stream, then there may not besufficient hydrogen to maintain reformer and boiler operatingtemperatures in fuel processor 15. Under this circumstance, methanolsupply is increased to produce additional heat to maintain the reformerand boiler temperatures.

Burner inlet 109 traverses monolithic structure 100 and carries anodeexhaust from fuel cell 20 before provision into burner 30. Disposingburner inlet 109 adjacent to a burner chamber 105 also heats theincoming anode exhaust, which reduces heat transferred to the anodeexhaust in the burner chamber 105.

In another embodiment, package 10 runs a heating medium from fuelprocessor 15 to fuel cell 20 to provide heat to fuel cell 20. In thiscase, package 10 includes plumbing configured to transport the heatingmedium from fuel processor 15 to fuel cell 20. As the term is usedherein, plumbing may comprise any tubing, piping and/or channeling thatcommunicates a gas or liquid from one location to a second location. Theplumbing may also comprise one or more valves, gates or other devices tofacilitate and control flow. Plumbing between burner 30 and fuel cell 20will be described in further detail below with respect to interconnect200.

In a specific embodiment, line 35 transports heated gases to fan 37,which moves the heated gases within fuel cell 20 and across the fuelcell stack and heat transfer appendages (FIG. 1C). Alternatively, theplumbing may be configured to transport the heating medium from burner30 to one or more heat transfer appendages. In this case, line 35 maycontinue through the fuel cell housing and open in the proximity of oneor more heat transfer appendages. A hole in the fuel cell housing thenallows line 35 to pass therethrough or connect to a port thatcommunicates the gases to plumbing inside the fuel cell for delivery tothe fuel cell stack and heat transfer appendage. For catalytic heatgeneration in fuel cell 20, the plumbing may also transport the heatingmedium to facilitate gaseous interaction with the catalyst, such asplumbing delivery to one or more bulkheads.

In one embodiment, the heating medium comprises heated gases exhaustedfrom burner 30. A catalytic burner or electrical resistance burneroperates at elevated temperatures. Cooling air exhausted from anelectric burner or product gases exhausted from a catalytic burner areoften greater than about 100 degrees Celsius when the gases leaves thefuel processor. For many catalytic burners, depending on the fuel sourceemployed, the heating medium is commonly greater than about 200 degreesCelsius when the heating medium leaves the fuel processor. These heatedgases are transported to the fuel cell for convective heat transfer inthe fuel cell, such as passing the heated gases over one or more heattransfer appendages 46 for convective heat transfer from the warmergases into the cooler heat transfer appendages.

In another embodiment, burner 30 is a catalytic burner and the heatingmedium comprises the fuel source. Catalytic combustion in burner 30 isoften incomplete and the burner exhaust gases include unused and gaseousmethanol. Fuel cell 20 then comprises a thermal catalyst thatfacilitates production of heat in the fuel cell in the presence ofmethanol. The fuel source is typically vaporized prior to reaching theburner to facilitate catalytic combustion. In this case, conduit 35transports the gaseous and unused methanol to the thermal catalyst infuel cell 20. Several suitable thermal catalyst arrangements fortransferring heat into heat transfer appendages 46 are described below(FIG. 2A). Suitable methanol catalysts, such as platinum or palladiumcoated onto alumina pellets, are also described above with respect tocatalyst 104 in burner 30.

In one embodiment, the heating medium is transported to the fuel cellduring a start-up period before the fuel cell begins generatingelectrical energy, e.g., in response to a request for electrical energy.Heating a fuel cell in this manner allows fuel cell component operatingtemperatures to be reached sooner and expedites warm-up time needed wheninitially turning on fuel cell 20. In another embodiment, the heatingmedium is transported from the fuel processor to the fuel cell during aperiod of non-activity in which the fuel cell does not generateelectrical energy and the component cools. Since many fuel cells requireelevated temperatures for operation and the electrical energy generatingprocess is exothermic, the fuel cell usually does not require externalheating during electrical energy generation. However, when electricalenergy generation ceases for an extended time and the component dropsbelow a threshold operating temperature, the heating medium may then betransported from the fuel processor to regain the operating temperatureand resume electrical energy generation. This permits operatingtemperatures in a fuel cell to be maintained when electrical energy isnot being generated by the fuel cell.

Although the present invention will primarily be described with respectto the reformer and burner shown in FIGS. 3A and 3B, it is anticipatedthat a fuel cell package may include other fuel processor designs. Manyarchitectures employ a planar reformer disposed on top or below to aplanar burner. Micro-channel designs fabricated in silicon commonlyemploy such stacked planar architectures may be used. Other fuelprocessors may be used that process fuel sources other than methanol.Fuel sources other than methanol were listed above, and processors forthese fuels are not detailed herein for sake of brevity. Furtherdescription of planar fuel processors suitable for use with the presentinvention are included in commonly owned patent application Ser. No.10/877,044 (now U.S. Pat. No. 7,604,673), which is incorporated byreference for all purposes.

Interconnect

One embodiment for combining a fuel cell and fuel processor in a commonpackage employs a fuel cell system interconnect. The interconnect isdisposed at least partially between the fuel cell and the fuelprocessor, and forms a structural and plumbing intermediary between thetwo.

Combining a fuel cell and a fuel processor in a common packageintroduces a number of potential obstacles, such as plumbingconnectivity, space, and operating temperature differences. Theinterconnect described herein invention overcomes many of theseobstacles to facilitate a fuel cell package with reduced size and formfactor.

FIG. 5A illustrates a perspective view of an interconnect 200 for use ina fuel cell package in accordance with one embodiment of the presentinvention. FIG. 3A shows interconnect 200 positioned relative to fuelprocessor 15 when assembled in a package. FIG. 5B shows interconnect 200coupled to the top plate 64 a of fuel cell 20. FIG. 5C illustrates theunderside of top plate 64 a in accordance with a specific embodiment ofthe present invention. FIG. 5D illustrates plumbing internal tointerconnect 200. FIG. 5E illustrates a top view of the interconnect 200and an arrangement of ports 208 that uniquely identifies interconnect200.

Referring initially to FIG. 5A, interconnect 200 includes a number ofsides 201 and a suitably rigid material, such as a metal. Side 201 ainterfaces with fuel processor 15; top side 201 b interfaces with fuelcell 20. Side 201 c services inlet plumbing to the fuel processor. Eachside 201 refers generally to an exterior face of interconnect 200, neednot be entirely flat, and includes one or more surfaces. Indeed, eachside 201 may include recessed or heightened features, as shown.Different sides and surface arrangements for interconnect 200 arepossible and contemplated.

Interconnect 200 may include one or more materials. In one embodiment,interconnect 200 is constructed from a suitably rigid material that addsstructural integrity to a fuel cell package and provides rigidconnectivity between a fuel cell and fuel processor. Many metals aresuitable for use with interconnect 200. In one embodiment, interconnect200 includes a single piece of fabricated material. Metals and hightemperature plastics are suitable for use in this case.

In a specific embodiment, interconnect 200 is machined from a singleblock of steel or aluminum. The material used in interconnect 200 may ormay not be thermally conductive, depending on thermal design of the fuelcell package.

Interconnect 200 includes plumbing for communicating any number of gasesand liquids between a fuel cell and fuel processor. For the fuel cellsystem 10 of FIG. 1C, plumbing serviced by interconnect 200 includes 1)a hydrogen line 39 from the fuel processor to the fuel cell, 2) a line38 returning unused hydrogen from the fuel cell back to the fuelprocessor, 3) an oxygen line 33 from the fuel cell to the fuelprocessor, and 4) a reformer or burner exhaust line 37 traveling fromthe fuel processor to the fuel cell. Other gas or liquid transfersbetween a fuel cell and fuel processor, in either direction, may beserviced by interconnect 200. In one embodiment, interconnect 200internally incorporates all plumbing for gases and liquids it transfersto minimize exposed tubing and package size.

Interconnect 200 includes a set of conduits 204 for fluid and gascommunication between fuel cell 20 and fuel processor 15. As the term isused herein, a conduit refers to a channel, tube, routing port, pipe, orthe like that permits gaseous or fluid communication between twolocations. For interconnect 200, each conduit 204 includes a channel 206(FIGS. 5A and 5D) within the interconnect 200 and a port 208 (oraperture) on each end of channel 206. For example, one conduit 204 a mayinclude a port 208 d that receives hydrogen from the fuel processor onone side 201 a of interconnect 200 and communicates the hydrogen—throughinterconnect 200—and to a port 208 a on side 201 b to the fuel cell.Each port 208 facilitates connectivity with interconnect 200. Whenassembled, each port 208 interfaces with plumbing from a fuel cell orfuel processor, or plumbing intermediaries therebetween.

In one embodiment, both fuel cell 20 and fuel processor 15 include fixedplumbing to interface with interconnect 200. The plumbing communicatesthe liquid or gas between a port 208 on interconnect 200 and afunctional portion of fuel cell 20 or fuel processor 15 (e.g., hydrogenfuel inlet to the fuel cell). FIG. 5C shows fixed plumbing channels 84,86, 88 and 90 disposed on an inner surface of the top plate 64 of fuelcell 20. Channels 84, 86, 88 and 90 communicate gases betweeninterconnect 200 and manifolds in the fuel cell stack 60. For example, afixed channel 84 on top plate 64 communicates hydrogen from interconnect200 to a hydrogen manifold in stack 60, which then delivers the hydrogento gas distribution channels in each bi-polar plate.

Fuel cell 20 and fuel processor 15 also include connections or portsthat mate with interconnect ports 208 to facilitate interface andproduct or reactant delivery. FIG. 5C illustrates mating ports 211 on atop plate 64 of fuel cell 20. FIG. 3A illustrates mating ports 209 onend plate 184 of fuel processor 15. A gasket may be disposed between endplate 184 and interconnect 200 to improve sealing. Similarly, a gasketmay be disposed between top plate 64 and interconnect 200. Although thefuel processor 15 and fuel cell 20 are shown with separate plates thatinterface with interconnect 200, other arrangements for interfacing withinterconnect 200 are suitable for use with the present invention. Forexample, although interconnect 200 interfaces with one side to fuel cell20 and another side to fuel processor 15, the present invention is notlimited to such simple geometric relationship. Alternatively, either thefuel cell 20 or fuel processor 15 interact with two or more sides ofinterconnect 200.

Referring now to the delivery of specific gases, interconnect 200communicates hydrogen from fuel processor 15 to fuel cell 20. A hydrogenconduit 204 a in interconnect 200 then forms part of a hydrogenprovision line 39 (FIG. 1C). For fuel processor 15 and fuel cell 20,hydrogen conduit 204 a receives hydrogen from a hydrogen channel 209included in fuel processor 15 (FIG. 3A) and outputs the hydrogen to ahydrogen channel 92 included in fuel cell 20 (FIGS. 5B and 5C). Line 39thus includes (in order of hydrogen delivery): reformer exit via channel209 in fuel processor 15, conduit 204 a in interconnect 200, and channel92 in fuel cell 20. Hydrogen conduit 204 a includes a channel 206 a andtwo ports 208 a and 208 d (FIG. 5A). Channel 206 a passes through thematerial of interconnect 200 from surface 201 a to surface 201 b. FIG.5D shows internal dimensions of channel 206 a. Hydrogen port 208 dinterfaces with hydrogen output channel 209 from fuel processor 15. Aportion of a gasket seals port 208 d and channel 209. Hydrogen port 208a interfaces with hydrogen channel 92 for fuel cell 20 via a port 211 aincluded in the bottom surface of top plate 64 (FIG. 5C).

Interconnect 200 also communicates unused hydrogen and anode exhaustfrom fuel cell 20 back to a burner fuel processor 15. A hydrogen conduit204 c in interconnect 200 then forms part of a hydrogen return line 38(FIG. 1C). Hydrogen conduit 204 c receives unused hydrogen from channel86 included in top plate 64 (FIGS. 5B and 5C) and outputs the anodeexhaust to a burner inlet 109 in the fuel processor. Line 38 thusincludes (in order of delivery): anode exit via channel 86 in fuel cell20, conduit 204 c in interconnect 200, and inlet 109 in fuel processor15. Conduit 204 c includes a channel 206 c and two ports 208 c and 208 b(FIG. 5A). Channel 206 c passes through the material of interconnect 200from surface 201 b to surface 201 a. FIG. 5D shows internal dimensionsof channel 206 c. Port 208 b interfaces with an anode exhaust inletchannel 109 in fuel processor 15. A portion of a gasket seals port 208 band channel 109. Port 208 c interfaces with anode exhaust channel 86 offuel cell 20 via a port 211 c included in the bottom surface of topplate 64 (FIG. 5C).

Interconnect 200 communicates heated oxygen and cathode exhaust fromfuel cell 20 to a burner in fuel processor 15. The heated oxygen is usedfor catalytic combustion in the burner, and increases thermal efficiencyof the package. An oxygen conduit 204 b in interconnect 200 then formspart of oxygen line 33 (FIG. 1C). Oxygen conduit 204 b receives heatedoxygen and air from channel 90 included in top plate 64 (FIGS. 5B and5C) and outputs the heated oxygen to a burner inlet in the fuelprocessor. Line 33 thus includes (in order of delivery): cathode exitvia channel 90 in fuel cell 20, conduit 204 b in interconnect 200, andan inlet to the burner in fuel processor 15. Conduit 204 b includes achannel 206 b and two ports 208 e and 208 f (FIG. 5A). Channel 206 bpasses through the material of interconnect 200 from surface 201 b tosurface 201 a. FIG. 5D shows internal dimensions of channel 206 b. Port208 f interfaces with a burner inlet in fuel processor 15. Port 208 einterfaces with cathode exhaust channel 90 of fuel cell 20 via a port211 b included in the bottom surface of top plate 64 (FIG. 5C).

Interconnect 200 additionally communicates burner exhaust from fuelprocessor 15 to heat transfer appendages in fuel cell 20. The burnerexhaust reacts with a catalyst disposed near the fuel cell to heat thefuel cell and expedite fuel cell start-up. A burner exhaust conduit 204d in interconnect 200 then forms part of exhaust line 35 (FIG. 1C).Conduit 204 d receives burner exhaust from a burner outlet in the fuelprocessor and outputs burner exhaust to a heating region 262 in the fuelcell (FIG. 2B). Line 35 thus includes (in order of delivery): a burnerexit in fuel processor 15, conduit 204 d in interconnect 200, andheating region 262 in fuel cell 20. Conduit 204 d includes a channel 206d and two ports 208 g and 208 h (FIG. 5A). Channel 206 d passes throughthe material of interconnect 200 from surface 201 a to surface thatfaces the body of the fuel cell. FIG. 5D shows internal dimensions ofchannel 206 d. Port 208 g interfaces with a burner outlet in fuelprocessor 15. A portion of a gasket seals port 208 g and the burneroutlet. Port 208 h opens to region 262 in the fuel cell 20.

Interconnect 200 is also responsible for fuel source delivery to fuelprocessor 15. A reformer fuel source inlet 81 receives methanol from afuel source feed (pump 21 b and an upstream storage device 16, see FIG.1C) and includes a conduit 206 e internal to interconnect 200 thatdelivers the methanol to a boiler in the fuel processor that heats themethanol before delivery to the reformer. A burner fuel source inlet 204f receives methanol from a second fuel source feed (a second pump 21 aand upstream storage device 16) and includes a conduit 206 f internal tointerconnect 200 that delivers the methanol to a boiler in the fuelprocessor that heats the methanol before delivery to the catalyticburner.

In general, interconnect 200 may include any suitable number of conduitsfor communicating fluids and gases between a fuel cell and fuelprocessor. From 1 to about 8 conduits is suitable for many micro fuelcell systems and packages. Each conduit may be dedicated to a particulargas or fluid. Dedicated conduits may be responsible for: oxygen,hydrogen, burner or reformer exhaust, methanol or another fuel source,air, or any other reactant or process gas or liquid used in a fuelprocessor or fuel cell. It is understood that some of these substancesmay go in either direction (or both) between a fuel cell and a fuelprocessor.

In general, a conduit 204 may communicate a gas or liquid between anyportion or portions of a fuel cell or fuel processor. For example, aconduit may receive a gas from a dedicated manifold in a fuel cell orfuel processor. Alternatively, a conduit may deliver a gas to a regionwithin a fuel cell, such as a volume that includes one or more heattransfer appendages. The conduits 204 may be variably configuredaccording to design demands. In one embodiment, an interconnect and itsconduits 204 are designed and configured to reduce volume of theintegrated fuel cell package. In another embodiment, conduits 204 aredesigned and configured to align with existing fluid channels andconduits of a fuel cell and fuel processor.

A gasket may also be employed to interface between interconnect 200 andthe fuel cell 20 or between interconnect 200 and fuel processor 15. Forexample, a gasket may be disposed during assembly between end plate 184of fuel processor 15 and interconnect 200. A gasket 260 betweeninterconnect 200 and fuel cell 20 is also discussed below.

One issue that arises with combining a fuel cell and fuel processor in acommon and compact package is operating temperature differences betweenthe two. Depending on the specific fuel cell, processor, and theirrespective catalysts, temperature differences between the two structuresin a compact package may vary significantly. For example, one suitablefuel processor 15 operates above 250° C., while fuel cell 20 typicallyoperates about 190° C. (or below). Putting the two objects in closeproximity introduces potential heat transfer, and resulting thermalefficiency losses in the fuel processor if the heat transfer cannot becontrolled.

Interconnect 200 is designed to reduce heat transfer between a fuelprocessor and a fuel cell. In one embodiment, the interconnect serves asan insulation for heat transfer between the fuel cell and the fuelprocessor and includes a low thermal conductance material. In anotherembodiment, the interconnect contains a minimal amount of material incontact with the fuel cell and/or fuel processor, which minimizesthermal conduction between the two components via the interconnect. Thisreduces material restrictions on interconnect 200.

FIG. 5F illustrates an expanded side view of the contact betweeninterconnect 200 and top plate 64 about a port 208 in accordance withone embodiment of the present invention. As shown, interconnect 200maintains one or more gaps 240 between one of its sides 201 the bottomsurface of plate 64. The gaps 240 may be left empty or filled with aninsulation (FIG. 6). Air gaps 240 each act as a layer of low thermalcapacity material and low thermal conductance insulation to minimizeheat transfer between the interconnect and the fuel processor or fuelcell.

Mating features 244 and 246 reduce surface area contact between facingsurfaces of each structure. This further reduces conductive heattransfer between the fuel cell and interconnect.

Mating features 244 include heightened portions 252 of each port 208that extend above a recessed surface 254 on side 201 b of interconnect200. FIG. 5F shows the mating arrangement 246 on the bottom surface oftop plate 64. Recessed surface 254 receives a distal end of 245 ofmating features 246 on the top plate 64. Mating features 244 and 246 areshaped in surface area so as to overlap in depth when interconnect 200and top plate 64 are coupled together.

Recessed surface 254 also receives a gasket 260 that facilitates sealingbetween interconnect 200 and top plate 64. Gasket 260 surrounds eachport 208 on surface 254. Gasket 260 is suitably compressible, andprevents contact between interconnect 200 and top plate 64 when thepackage has been assembled. More specifically, gasket 260 is shaped toborder the outside of heightened portions 252 of each port 208, andinterrupts the distal end of 245 of mating features 246 on top plate 64before they contact with recessed surface 254. Gasket 260 thus improvessealing between the two structures and their respective channels, andimproves gaseous flow in the fuel cell system. In one embodiment, gasket260 includes a custom cut graphoil gasket shaped to follow the contoursof recessed surface 254, or another high temperature, low thermalconductance and compliant material. The low thermal conductance gasket260 also reduces heat transfer between top plate 64 and interconnect200.

Heightened portions 252 of each port 208 also provide improvedgasketing. More specifically, heightened portions 252 prevent extrusionof gasket 260 (resting on recessed surface 254) into a channel 206 orscrew hole 215 that otherwise might occur during assembly in the absenceof heightened portions 252.

Mating features 244 and 246 also facilitate alignment between the twostructures. Collectively, the shape and spatial arrangement of ports 208and holes 211 (and their mating features 244 and 246) provides a uniquestructural interface between interconnect 200 and top plate 64 of fuelcell 20 when interconnect 200 attaches to top plate 64. FIG. 5A showsone exemplary ‘crop circle’ configuration that includes a series ofcircles. Top plate 64 has a matching configuration 258 on its bottomside. When interconnect 200 and top plate 64 are coupled or attachedtogether, the shape and spatial arrangement of ports 208 and screw holes211 deterministically align and locate top plate 64 relative tointerconnect 200. Joining the two pieces also provides forces thatresist relative motion (translations and rotations in three dimensions)between top plate 64 and interconnect 200. Other spatial arrangementsand configurations are suitable and contemplated. For example, thenumber of circles, spacing or area arrangement may be altered.

Screw holes 215 permit mechanical coupling between interconnect 200 andtop plate 64. Screw holes 215 also include heightened features thatfacilitate alignment, and add to the unique structural interface,between interconnect 200 and fuel cell 20.

Interconnect 200 has multiple advantages. Typically, a fuel cell systemincludes significant amount of plumbing between a fuel cell and fuelprocessor. Such plumbing consumes considerable space. One advantage ofinterconnect 200 is that it reduces size of a single package containingboth a fuel processor and fuel cell by eliminating numerous tubes andadditional plumbing associated with a disparate fuel cell and fuelprocessor. Interconnect 200 also avoids the need for brazing metaltubes, which affects manufacture. Although the present invention mayinclude one or more brazed metal tubes, reducing the number of pipeswith interconnect 200 decreases manufacturing complexity.

While interconnect 200 has been described with respect to a separatestructure that separably attaches to both a fuel cell and a fuelprocessor, it is understood that the interconnect may be included as anintegral part of a fuel cell, or as an integral part of a fuelprocessor, that the other attaches to.

Package Insulation

Many fuel cells and fuel processors operate at elevated temperatures.Burner 30 temperatures from about 200 degrees Celsius to about 800degrees Celsius are common. Many fuel cells 20 operate at elevatedtemperatures during electrical energy production. The electrochemicalreaction responsible for hydrogen consumption and electrical energygeneration typically requires an elevated temperature. Starttemperatures in the MEA layer 62 and its constituent parts greater than150 degrees Celsius are common.

The ambient environment around the fuel cell package is cooler, andtypically less than 40 degrees Celsius. Heat loss from the fuel cell orfuel processor to the ambient environment decreases efficiency of eachdevice, and of the fuel cell package.

In one embodiment, a fuel cell package of the present invention includesinsulation that reduces heat loss from a fuel cell or a fuel processor.The insulation is disposed at least partially around the fuel celland/or fuel processor and beneath the package housing. The insulationreduces heat transfer from the fuel cell and/or fuel processor to thepackage housing, which reduces temperatures for the housing. This inturn reduces heat loss to the ambient environment. Thus, the insulationkeeps heat in the package and increases efficiency for the componentsrunning at elevated temperatures.

FIG. 6 shows a perspective view of insulation 320 disposed aboutinternal components and under the housing of the fuel cell package 440of FIG. 4C in accordance with a specific embodiment of the presentinvention. FIG. 4B also shows insulation 320 disposed around the fuelcell 20 and fuel processor 15. In both cases, insulation 320 has beenshown with some transparency to facilitate illustration and description.As shown, insulation 320 disposed at least partially around the outsideof fuel cell 20 to minimize heat loss from the fuel cell. Insulation 320is also disposed at least partially around fuel processor 15 to reduceheat loss from the fuel processor.

Insulation 320 may include one or more layers of a low thermalconductance material. The insulation layer may be wrapped around thefuel cell 20, fuel processor 15 and/or fuel cell system package.Thickness for the insulation layer and the number of wrappings aroundeach component may be varied according to design. Increasing thethickness or the number of wrappings decreases heat loss. In oneembodiment, the insulation is selected and configured such that thesurface of fuel cell package 440 maintains a desired temperature.Standards imposed on consumer-electronics devices may mandate surfacetemperature of electronics devices such as a tethered fuel cell packageto be less than some predetermined level, and insulation 320 may bedesigned to regularly meet this level. Some consumer-electronics devicestandards require a surface temperature less than 50° C. A thicknessfrom about 1 millimeter to about 10 millimeters is suitable for somedesigns. In a specific embodiment, insulation 320 has a thickness ofabout 2 millimeters and is wrapped twice about the fuel cell and fuelprocessor. In a specific embodiment, one layer of material is disposedon the fuel cell between manifolds, while a second layer surrounds theentire fuel cell.

Insulation 320 may include a commercially available sheet of insulation.One suitable commercially available insulation material comprisesaerogel insulation as provided by Aspen Systems, Inc. of Marlborough,Mass. Other forms of insulation may be used. One of skill in the artwill appreciate the wide variety of commercially available insulationproducts useful herein to achieve a desired temperature drop.

In a specific embodiment, an insulation layer is disposed around a fuelcell and a processor in addition to a layer of insulation around thefuel cell system package. This dual insulation set further maintainsheat in the heat generating components of the fuel cell system.

A fuel cell package may also include one or more air gaps in addition toinsulation 320. The gaps may be disposed between the insulation andpackage, between the insulation and the fuel cell or between theinsulation and the fuel processor. A fan may move air through the gapsto facilitate heat dissipation away from a housing or surface of thepackage.

CONCLUSION

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents thatfall within the scope of this invention which have been omitted forbrevity's sake. For example, although the present invention has beendescribed systems and methods operating on a fuel cell system andpackage, many of the methods and techniques described constitute systemcontrols and will comprise digital control applied by a processor thatimplements instructions from stored software. While not described indetail, implementation of such digital control onto a mechanical systemis well known to one of skill in the art and the present invention maythus relate to instructions stored in software capable of carrying outmethods described herein. It is therefore intended that the scope of theinvention should be determined with reference to the appended claims.

1. A fuel cell package for providing electrical energy, the fuel cellpackage comprising: a fuel processor that includes: a reformerconfigured to receive a fuel source, configured to output hydrogen, andincluding a catalyst that facilitates the production of hydrogen fromthe fuel source, a heater configured to generate heat for transfer tothe reformer; a fuel cell configured to generate electrical energy usinghydrogen output by the fuel processor; and an interconnect disposed atleast partially sandwiched between the fuel cell and the fuel processorand including a set of conduits that each communicate a liquid or gasbetween the fuel processor and the fuel cell, wherein the interconnectserves as passive insulation for conductive heat transfer between thefuel cell and the fuel processor; wherein the interconnect contains aside having a port, at least one flat portion, and at least one recessedarea; wherein the side of the interconnect further contains at least oneheightened portion and a top plate of the fuel cell contains at leastone recessed area, and wherein the at least one heightened portion ofthe side of the interconnect is separated from the at least one recessedarea of the top plate of the fuel cell by a gap.
 2. The fuel cellpackage of claim 1 wherein each conduit passes from one surface of theinterconnect to another surface of the interconnect.
 3. The fuel cellpackage of claim 1 wherein the interconnect includes a hydrogen conduitthat receives hydrogen from a hydrogen channel in the fuel processor andoutputs the hydrogen to a hydrogen channel in the fuel cell.
 4. The fuelcell package of claim 1 wherein the interconnect includes an oxygenconduit that receives oxygen from an oxygen channel in the fuel cell andoutputs the oxygen to an oxygen channel in the fuel processor.
 5. Thefuel cell package of claim 1 wherein the interconnect includes a heatingconduit that receives a heating medium from the fuel processor andoutputs the heating medium to the fuel cell.
 6. The fuel cell package ofclaim 1 wherein the interconnect includes a hydrogen return channel thatreceives unused hydrogen from the fuel cell and outputs the unusedhydrogen to the fuel processor.
 7. A fuel cell package for providingelectrical energy, the fuel cell package comprising: a fuel processorthat includes a reformer having an interface portion that can connect toa fuel source, and also having an output, the reformer including acatalyst that facilitates the production of hydrogen from the fuelsource, the reformed designed to expel the hydrogen through the output;a heater configured to generate heat for transfer to the reformer; afuel cell configured to generate electrical energy using hydrogen outputby the fuel processor; and an interconnect disposed at least partiallysandwiched between the fuel cell and the fuel processor and including aset of conduits that each communicate a liquid or gas between the fuelprocessor and the fuel cell, wherein the interconnect itself serves aspassive insulation for conductive heat transfer between the fuel celland the fuel processor by virtue of it being at least partiallysandwiched between the fuel cell and the fuel processor.
 8. The fuelcell package of claim 7 wherein the interconnect is a separate piecefrom the fuel processor and from the fuel cell before assembly of thefuel cell package and attaches to the fuel processor and attaches to thefuel cell after assembly.
 9. The fuel cell package of claim 7 whereinthe fuel cell includes a plate that couples to the interconnect, theplate including a set of channels that each open to a conduit includedin the interconnect.
 10. The fuel cell package of claim 9 wherein theinterconnect includes mating features that contact the plate after thefuel cell package has been assembled.
 11. The fuel cell package of claim10 wherein the mating reduces surface area contact between theinterconnect and the fuel cell relative to the amount of surface areacontact between the interconnect and the fuel cell without the matingfeatures.
 12. The fuel cell package of claim 11 further comprising agasket disposed between the interconnect and the plate.
 13. The fuelcell package of claim 12 wherein the mating features on the interconnectinclude heightened features that prevent extrusion of the gasket into aconduit.
 14. A method for assembling a fuel cell package, the methodcomprising: providing a fuel processor that includes: a reformer havingan interface portion that can connect to a fuel source, and also havingan output, the reformer including a catalyst that facilitates theproduction of hydrogen from the fuel source, the reformed designed toexpel the hydrogen through the output; a heater configured to generateheat for transfer to the reformer; providing a fuel cell configured togenerate electrical energy using hydrogen output by the fuel processor;and connecting the fuel processor to the fuel cell using an interconnectpartially sandwiched between the fuel cell and the fuel processor andincluding a set of conduits that each communicate a liquid or gasbetween the fuel processor and the fuel cell, wherein the interconnectitself serves as passive insulation for conductive heat transfer betweenthe fuel cell and the fuel processor by virtue of it being at leastpartially sandwiched between the fuel cell and the fuel processor. 15.The method of claim 14, wherein liquids or gasses traveling from thefuel processor to the fuel cell travel in a first direction from thefuel processor then in a second direction into a top plate of the fuelcell, wherein the first direction is perpendicular to the seconddirection.
 16. The method of claim 15, wherein liquids or gassestraveling from the fuel cell to the fuel processor travel in a thirddirection from the top plate of the fuel cell then in a fourth directioninto the fuel processor, wherein the third direction is perpendicular tothe fourth direction.
 17. A fuel cell package for providing electricalenergy, the fuel cell package comprising: means for processing fuel, themeans for processing fuel including: means for reforming the fuel byreceiving a fuel source, using a catalyst to facilitate the productionof hydrogen from the fuel source, and outputting hydrogen; and means forgenerating heat transfer to the means for reforming; means forgenerating electrical energy using hydrogen output by the fuelprocessor; and means for interconnecting the means for processing andthe means for generating, wherein the means for interconnecting isdisposed at least partially sandwiched between the means for processingand the means for generating and acting as passive insulation forconductive heat transfer between the means for processing and means forgenerating.
 18. The fuel cell package of claim 17, wherein the means forinterconnecting has a side having a port, at least one flat portion, andat least one recessed area; wherein the side of the means forinterconnecting further contains at least one heightened portion and atop plate of the means for generating contains at least one recessedarea, and wherein the at least one heightened portion of the side of themeans for interconnecting is separated from the at least one recessedarea of the top plate by a gap.
 19. The fuel cell package of claim 18,wherein the gap is filled with insulation.
 20. The fuel cell package ofclaim 18, wherein the gap is empty.